Resist composition, method of forming resist pattern, compound, acid generator, and method of producing compound

ABSTRACT

A resist composition including a compound represented by formula (b1) in which R b1  represents an aryl group which may have a substituent; R b2  and R b3  each independently represents an aryl group which may have a substituent or an alkyl group which may have a substituent; provided that at least one of the aryl group represented by R b1  and the aryl group or the alkyl group represented by R b2  or R b3  has a substituent containing a halogen atom, and at least one of the aryl group represented by R b1  and the aryl group or the alkyl group represented by R b2  or R b3  has a substituent containing a sulfonyl group; and X −  represents a counteranion

This application is a divisional of U.S. application Ser. No.16/420,956, filed May 23, 2019, which claims priority to Japanese PatentApplication No. 2018-101876, filed May 28, 2018, the contents of whichare incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a resist composition, a method offorming a resist pattern, a compound, an acid generator, and a method ofproducing a compound.

DESCRIPTION OF RELATED ART

In lithography techniques, for example, a resist film composed of aresist material is formed on a substrate, and the resist film issubjected to selective exposure, followed by development, therebyforming a resist pattern having a predetermined shape on the resistfilm. A resist material in which the exposed portions of the resist filmbecome soluble in a developing solution is called a positive-type, and aresist material in which the exposed portions of the resist film becomeinsoluble in a developing solution is called a negative-type.

In recent years, in the production of semiconductor elements and liquidcrystal display elements, advances in lithography techniques have led torapid progress in the field of pattern miniaturization. Typically, theseminiaturization techniques involve shortening the wavelength (increasingthe energy) of the exposure light source. Conventionally, ultravioletradiation typified by g-line and i-line radiation has been used, butnowadays KrF excimer lasers and ArF excimer lasers are used in massproduction. Furthermore, research is also being conducted intolithography techniques that use an exposure light source having awavelength shorter (energy higher) than these excimer lasers, such aselectron beam (EB), extreme ultraviolet radiation (EUV), and X ray.

Resist materials for use with these types of exposure light sourcesrequire lithography properties such as a high resolution capable ofreproducing patterns of minute dimensions, and a high level ofsensitivity to these types of exposure light sources.

As a resist material that satisfies these conditions, a chemicallyamplified composition is used, which includes a base material componentthat exhibits a changed solubility in a developing solution under theaction of acid and an acid-generator component that generates acid uponexposure.

For example, in the case where the developing solution is an alkalideveloping solution (alkali developing process), a chemically amplifiedpositive resist which contains, as a base component (base resin), aresin which exhibits increased solubility in an alkali developingsolution under action of acid, and an acid generator is typically used.If a resist film formed using such a resist composition is selectivelyexposed at the time of forming a resist pattern, in exposed areas, acidis generated from the acid generator component, and the polarity of thebase resin increases by the action of the generated acid, thereby makingthe exposed areas of the resist film soluble in the alkali developingsolution. Thus, by conducting alkali developing, the unexposed portionsof the resist film remain to form a positive resist pattern.

On the other hand, when such a base resin is applied to a solventdeveloping process using a developing solution containing an organicsolvent (organic developing solution), the solubility of the exposedportions in an organic developing solution is decreased. As a result,the unexposed portions of the resist film are dissolved and removed bythe organic developing solution, and a negative resist pattern in whichthe exposed portions of the resist film are remaining is formed. Such asolvent developing process for forming a negative-tone resistcomposition is sometimes referred to as “negative-tone developingprocess”.

In general, the base resin used for a chemically amplified resistcomposition contains a plurality of structural units for improvinglithography properties and the like.

For example, in the case of a resin composition which exhibits increasedsolubility in an alkali developing solution by the action of acid, astructural unit containing an acid decomposable group which isdecomposed by the action of acid generated from an acid generatorcomponent and exhibits increased polarity. Further, a structural unitcontaining a lactone-containing cyclic group or a structural unitcontaining a polar group such as a hydroxy group is used in combination.

Further, in the formation of a resist pattern, the behavior of acidgenerated from the acid generator component upon exposure is one of thefactors which has large influence on the lithography properties.

As the acid generator used in a chemically amplified resist composition,various kinds have been proposed. For example, onium salt acidgenerators such as iodonium salts and sulfonium salts; oxime sulfonateacid generators; diazomethane acid generators; nitrobenzylsulfonate acidgenerators; iminosulfonate acid generators; and disulfone acidgenerators are known.

As onium salt acid generators, those which have an onium ion such astriphenylsulfonium in the cation moiety are mainly used. Generally, asthe anion moiety for onium salt acid generators, an alkylsulfonate ionor a fluorinated alkylsulfonate ion in which part or all of the hydrogenatoms within the aforementioned alkylsulfonate ion has been substitutedwith fluorine atoms is typically used.

As the lithography technique further progresses and the miniaturizationof the resist pattern progresses more and more, for example, a target ofthe lithography performed by electron beams and EUV is to form fineresist patterns of several tens of nanometers. As the size of the resistpattern becomes smaller, the resist composition is required to have ahigh sensitivity to the exposure dose, and good lithography propertiessuch as reduced roughness.

Patent Literature 1 describes using an onium salt acid generator havinga sulfonium cation with a sulfonyl group introduced in order to enhancethe sensitivity of the resist.

Further, Patent Literature 2 describes using an onium salt acidgenerator having a sulfonium cation with a fluorine atom introduced inorder to enhance the sensitivity of the resist.

DOCUMENTS OF RELATED ART Patent Literature

[Patent Literature 1] Japanese Patent No. 4292981

[Patent Literature 2] Japanese Patent No. 4411042

SUMMARY OF THE INVENTION

However, an onium salt acid generator having a sulfonium cation with asulfonyl group or a fluorine atom introduced had concerns in thatlithography properties such as roughness may be adversely affected.

The present invention takes the above circumstances into consideration,with an object of providing a novel compound useful as an acid generatorfor a resist composition, an acid generator using the compound, anintermediate compound useful as an intermediate of the compound, aresist composition containing the acid generator, and a method offorming a resist pattern using the resist composition.

For solving the above-mentioned problems, the present invention employsthe following aspects.

A first aspect of the present invention is a resist composition whichgenerates acid upon exposure and exhibits changed solubility in adeveloping solution under action of acid, the resist compositionincluding a base component (A) which exhibits changed solubility in adeveloping solution under action of acid, and an acid generator (B1)containing a compound represented by general formula (b1) shown below.

In the formula, R^(b1) represents an aryl group which may have asubstituent; R^(b2) and R^(b3) each independently represents an arylgroup which may have a substituent or an alkyl group which may have asubstituent; R^(b2) and R^(b3) may be mutually bonded to form a ringwith the sulfur atom; provided that at least one of the aryl grouprepresented by R^(b1) and the aryl group or the alkyl group representedby R^(b2) or R^(b3) has a substituent containing a halogen atom, and atleast one of the aryl group represented by R^(b1) and the aryl group orthe alkyl group represented by R^(b2) or R^(b3) has a substituentcontaining a sulfonyl group; and X⁻ represents a counteranion.

A second aspect of the present invention is a method of forming a resistpattern, including: using a resist composition according to the firstaspect to form a resist film, exposing the resist film, and developingthe exposed resist film to form a resist pattern.

A third aspect of the present invention is a compound represented bygeneral formula (b1) shown below.

In the formula, R^(b1) represents an aryl group which may have asubstituent; R^(b2) and R^(b3) each independently represents an arylgroup which may have a substituent or an alkyl group which may have asubstituent;

R^(b2) and R^(b3) may be mutually bonded to form a ring with the sulfuratom; provided that at least one of the aryl group represented by R^(b1)and the aryl group or the alkyl group represented by R^(b2) or R^(b3)has a substituent containing a halogen atom, and at least one of thearyl group represented by R^(b1) and the aryl group or the alkyl grouprepresented by R^(b2) or R^(b3) has a substituent containing a sulfonylgroup; and X⁻ represents a counteranion.

A fourth aspect of the present invention is an acid generator includinga compound of the third aspect.

A fifth aspect of the present invention is a compound represented bygeneral formula (bp-1) shown below.

In the formula, R^(p1) represents an aryl group which may have asubstituent; R^(p2) and R^(p3) each independently represents an arylgroup which may have a substituent or an alkyl group which may have asubstituent;

R^(p2) and R^(p3) may be mutually bonded to form a ring with the sulfuratom; provided that at least one of the aryl group represented by R^(p1)and the aryl group or the alkyl group represented by R^(p2) or R^(p3)has a substituent containing a halogen atom, and at least one of thearyl group represented by R^(p1) and the aryl group or the alkyl grouprepresented by R^(p2) or R^(p3) has a group represented by the formula:—SR^(p4) as a substituent; R^(p4) represents an alkyl group; and Xp⁻represents a counteranion.

A sixth aspect of the present invention is a method of producing acompound, the method including: oxidizing a compound represented bygeneral formula (bp-1) shown below to obtain a compound represented bygeneral formula (b1-1) shown below.

In the formula, R^(p1) represents an aryl group which may have asubstituent; R^(p2) and R^(p3) each independently represents an arylgroup which may have a substituent or an alkyl group which may have asubstituent;

R^(p2) and R^(p3) may be mutually bonded to form a ring with the sulfuratom; provided that at least one of the aryl group represented by R^(p1)and the aryl group or the alkyl group represented by R^(p2) or R^(p3)has a substituent containing a halogen atom, and at least one of thearyl group represented by R^(p1) and the aryl group or the alkyl grouprepresented by R^(p2) or R^(p3) has a group represented by the formula:—SO₂—R^(p4) as a substituent; R^(p4) represents an alkyl group; and Xp⁻represents a counteranion.

In the formula, R^(b11) represents an aryl group which may have asubstituent; R^(b12) and R^(b13) each independently represents an arylgroup which may have a substituent or an alkyl group which may have asubstituent; R^(b12) and R^(b13) may be mutually bonded to form a ringwith the sulfur atom; provided that at least one of the aryl grouprepresented by R^(b1) and the aryl group or the alkyl group representedby R^(b12) or R^(b13) has a substituent containing a halogen atom, andat least one of the aryl group represented by R^(b11) and the aryl groupor the alkyl group represented by R^(b12) or R^(b13) has a grouprepresented by the formula: —SR^(p4) as a substituent;

R^(p4) represents an alkyl group; and Xp⁻ represents a counteranion.

Another aspect of the present invention is a resist composition whichgenerates acid upon exposure and exhibits changed solubility in adeveloping solution under action of acid, the resist compositionincluding a base component (A) which exhibits changed solubility in adeveloping solution under action of acid, and at least one compound(D11) selected from the group consisting of a compound represented bygeneral formula (d1-1) shown below, a compound represented by generalformula (d1-2) shown below and a compound represented by general formula(d1-3) shown below.

In the formulae, Rd¹ to Rd⁴ represent a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, provided that,the carbon atom adjacent to the sulfur atom within the Rd² in theformula (d1-2) has no fluorine atom bonded thereto; Yd¹ represents asingle bond or a divalent linking group; m is an integer of 1 or more;and each M^(m+) independently represents the sulfonium cation in theaforementioned formula (b1).

According to the present invention, there is provided a novel compounduseful as an acid generator for a resist composition, an acid generatorusing the compound, an intermediate compound useful as an intermediateof the compound, a resist composition containing the acid generator, anda method of forming a resist pattern using the resist composition.

According to the resist composition of the present invention,sensitivity can be enhanced in the formation of a resist pattern, and itbecomes possible to form a resist pattern exhibiting good lithographyproperties (reduced roughness, and the like).

DETAILED DESCRIPTION OF THE INVENTION

In the present description and claims, the term “aliphatic” is arelative concept used in relation to the term “aromatic”, and defines agroup or compound that has no aromaticity.

The term “alkyl group” includes linear, branched or cyclic, monovalentsaturated hydrocarbon, unless otherwise specified. The same applies forthe alkyl group within an alkoxy group.

The term “alkylene group” includes linear, branched or cyclic, divalentsaturated hydrocarbon, unless otherwise specified.

A “halogenated alkyl group” is a group in which part or all of thehydrogen atoms of an alkyl group is substituted with a halogen atom.Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

A “fluorinated alkyl group” or a “fluorinated alkylene group” is a groupin which part or all of the hydrogen atoms of an alkyl group or analkylene group have been substituted with a fluorine atom.

The term “structural unit” refers to a monomer unit that contributes tothe formation of a polymeric compound (resin, polymer, copolymer).

The case of describing “may have a substituent” includes both of thecase where the hydrogen atom (—H) is substituted with a monovalent groupand the case where the methylene group (—CH₂—) is substituted with adivalent group.

The term “exposure” is used as a general concept that includesirradiation with any form of radiation.

A “structural unit derived from an acrylate ester” refers to astructural unit that is formed by the cleavage of the ethylenic doublebond of an acrylate ester.

An “acrylate ester” refers to a compound in which the terminal hydrogenatom of the carboxy group of acrylic acid (CH₂═CH—COOH) has beensubstituted with an organic group.

The acrylate ester may have the hydrogen atom bonded to the carbon atomon the α-position substituted with a substituent. The substituent(R^(α0)) that substitutes the hydrogen atom bonded to the carbon atom onthe α-position is an atom other than hydrogen or a group, and examplesthereof include an alkyl group of 1 to 5 carbon atoms and a halogenatedalkyl group of 1 to 5 carbon atoms. Further, an acrylate ester havingthe hydrogen atom bonded to the carbon atom on the α-positionsubstituted with a substituent (R^(α0)) in which the substituent hasbeen substituted with a substituent containing an ester bond (e.g., anitaconic acid diester), or an acrylic acid having the hydrogen atombonded to the carbon atom on the α-position substituted with asubstituent (R^(α0)) in which the substituent has been substituted witha hydroxyalkylgroup or a group in which the hydroxy group within ahydroxyalkyl group has been modified (e.g., α-hydroxyalkyl acrylateester) can be mentioned as an acrylate ester having the hydrogen atombonded to the carbon atom on the α-position substituted with asubstituent. A carbon atom on the α-position of an acrylate ester refersto the carbon atom bonded to the carbonyl group, unless specifiedotherwise.

Hereafter, an acrylate ester having the hydrogen atom bonded to thecarbon atom on the α-position substituted with a substituent issometimes referred to as “α-substituted acrylate ester”. Further,acrylate esters and α-substituted acrylate esters are collectivelyreferred to as “(α-substituted) acrylate ester”.

A “structural unit derived from acrylamide” refers to a structural unitthat is formed by the cleavage of the ethylenic double bond ofacrylamide.

The acrylamide may have the hydrogen atom bonded to the carbon atom onthe α-position substituted with a substituent, and may have either orboth terminal hydrogen atoms on the amino group of acrylamidesubstituted with a substituent. A carbon atom on the α-position of anacrylamide refers to the carbon atom bonded to the carbonyl group,unless specified otherwise.

As the substituent which substitutes the hydrogen atom on the α-positionof acrylamide, the same substituents as those described above for thesubstituent (R^(α0)) on the α-position of the aforementioned α-positionof the aforementioned α-substituted acrylate ester can be mentioned.

A “structural unit derived from hydroxystyrene” refers to a structuralunit that is formed by the cleavage of the ethylenic double bond ofhydroxystyrene. A “structural unit derived from a hydroxystyrenederivative” refers to a structural unit that is formed by the cleavageof the ethylenic double bond of a hydroxystyrene derivative.

The term “hydroxystyrene derivative” includes compounds in which thehydrogen atom at the α-position of hydroxystyrene has been substitutedwith another substituent such as an alkyl group or a halogenated alkylgroup; and derivatives thereof. Examples of the derivatives thereofinclude hydroxystyrene in which the hydrogen atom of the hydroxy grouphas been substituted with an organic group and may have the hydrogenatom on the α-position substituted with a substituent; andhydroxystyrene which has a substituent other than a hydroxy group bondedto the benzene ring and may have the hydrogen atom on the α-positionsubstituted with a substituent. Here, the α-position (carbon atom on theα-position) refers to the carbon atom having the benzene ring bondedthereto, unless specified otherwise.

As the substituent which substitutes the hydrogen atom on the α-positionof hydroxystyrene, the same substituents as those described above forthe substituent on the α-position of the aforementioned α-substitutedacrylate ester can be mentioned.

A “structural unit derived from vinylbenzoic acid or a vinylbenzoic acidderivative” refers to a structural unit that is formed by the cleavageof the ethylenic double bond of vinylbenzoic acid or a vinylbenzoic acidderivative.

The term “vinylbenzoic acid derivative” includes compounds in which thehydrogen atom at the α-position of vinylbenzoic acid has beensubstituted with another substituent such as an alkyl group or ahalogenated alkyl group; and derivatives thereof. Examples of thederivatives thereof include benzoic acid in which the hydrogen atom ofthe carboxy group has been substituted with an organic group and mayhave the hydrogen atom on the α-position substituted with a substituent;and benzoic acid which has a substituent other than a hydroxy group anda carboxy group bonded to the benzene ring and may have the hydrogenatom on the α-position substituted with a substituent. Here, theα-position (carbon atom on the α-position) refers to the carbon atomhaving the benzene ring bonded thereto, unless specified otherwise.

The term “styrene derivative” includes compounds in which the hydrogenatom at the α-position of styrene has been substituted with anothersubstituent such as an alkyl group or a halogenated alkyl group; andderivatives thereof. Examples of the derivatives thereof includehydroxystyrene which has a substituent other than a hydroxy group bondedto the benzene ring and may have the hydrogen atom on the α-positionsubstituted with a substituent. Here, the α-position (carbon atom on theα-position) refers to the carbon atom having the benzene ring bondedthereto, unless specified otherwise.

A “structural unit derived from styrene” or “structural unit derivedfrom a styrene derivative” refers to a structural unit that is formed bythe cleavage of the ethylenic double bond of styrene or a styrenederivative.

As the alkyl group as a substituent on the α-position, a linear orbranched alkyl group is preferable, and specific examples include alkylgroups of 1 to 5 carbon atoms, such as a methyl group, an ethyl group, apropyl group, an isopropyl group, an n-butyl group, an isobutyl group, atert-butyl group, a pentyl group, an isopentyl group and a neopentylgroup.

Specific examples of the halogenated alkyl group as the substituent onthe α-position include groups in which part or all of the hydrogen atomsof the aforementioned “alkyl group as the substituent on the α-position”are substituted with halogen atoms. Examples of the halogen atom includea fluorine atom, a chlorine atom, a bromine atom and an iodine atom, anda fluorine atom is particularly desirable.

Specific examples of the hydroxyalkyl group as the substituent on theα-position include groups in which part or all of the hydrogen atoms ofthe aforementioned “alkyl group as the substituent on the α-position”are substituted with a hydroxy group. The number of hydroxy groupswithin the hydroxyalkyl group is preferably 1 to 5, and most preferably1.

In the present specification and claims, some structures represented bychemical formulae may have an asymmetric carbon, such that an enantiomeror a diastereomer may be present. In such a case, the one formularepresents all isomers. The isomers may be used individually, or in theform of a mixture.

(Resist Composition)

The resist composition according to a first aspect of the presentinvention is a resist composition which generates acid upon exposure andexhibits changed solubility in a developing solution under action ofacid. In one embodiment, the resist composition includes a basecomponent (A) (hereafter, sometimes referred to as “component (A)”)which exhibits changed solubility in a developing solution under actionof acid, and an acid-generator component (B) (hereafter, sometimesreferred to as “component (B)”) which generates acid upon exposure.

When a resist film is formed using the resist composition according tothe present embodiment and the formed resist film is subjected to aselective exposure, acid is generated at exposed portions, and thegenerated acid acts on the component (A) to change the solubility of thecomponent (A) in a developing solution, whereas the solubility of thecomponent (A) in a developing solution is not changed at unexposedportions, thereby generating difference in solubility in a developingsolution between exposed portions and unexposed portions. Therefore, bysubjecting the resist film to development, the exposed portions of theresist film are dissolved and removed to form a positive-tone resistpattern in the case of a positive resist, whereas the unexposed portionsof the resist film are dissolved and removed to form a negative-toneresist pattern in the case of a negative resist.

In the present specification, a resist composition which forms apositive resist pattern by dissolving and removing the exposed portionsof the resist film is called a positive resist composition, and a resistcomposition which forms a negative resist pattern by dissolving andremoving the unexposed portions of the resist film is called a negativeresist composition.

The resist composition of the present embodiment may be either apositive resist composition or a negative resist composition. Further,in the present embodiment, the resist composition may be applied to analkali developing process using an alkali developing solution in thedeveloping treatment, or a solvent developing process using a developingsolution containing an organic solvent (organic developing solution) inthe developing treatment, and preferably a solvent developing process.

The resist composition of the present embodiment has a function ofgenerating acid upon exposure, and the component (A) may generate acidupon exposure, in addition to the component (B).

In the case where the component (A) generates acid upon exposure, thecomponent (A) is a “base component which generates acid upon exposureand exhibits changed solubility in a developing solution under action ofacid”.

In the case where the component (A) is a base component which generatesacid upon exposure and exhibits changed solubility in a developingsolution under action of acid, the component (A1) described later ispreferably a polymeric compound which generates acid upon exposure andexhibits changed solubility in a developing solution under action ofacid. As the polymeric compound, a resin having a structural unit whichgenerates acid upon exposure may be mentioned. As the structural unitwhich generates acid upon exposure, any conventionally known structuralunit may be used.

<Component (A)>

In the resist composition of the present embodiment, the component (A)is a base component which exhibits changed solubility in a developingsolution under action of acid.

In the present invention, the term “base component” refers to an organiccompound capable of forming a film, and is preferably an organiccompound having a molecular weight of 500 or more. When the organiccompound has a molecular weight of 500 or more, the film-forming abilityis improved, and a resist pattern of nano level can be easily formed.

The organic compound used as the base component is broadly classifiedinto non-polymers and polymers.

In general, as a non-polymer, any of those which have a molecular weightin the range of 500 to less than 4,000 is used. Hereafter, a “lowmolecular weight compound” refers to a non-polymer having a molecularweight in the range of 500 to less than 4,000.

As a polymer, any of those which have a molecular weight of 1,000 ormore is generally used. Hereafter, a “resin” or a “polymer” refers to apolymer having a molecular weight of 1,000 or more.

As the molecular weight of the polymer, the weight average molecularweight in terms of the polystyrene equivalent value determined by gelpermeation chromatography (GPC) is used.

In the case where the resist composition of the present embodiment is a“negative resist composition for alkali developing process” which formsa negative resist pattern in an alkali developing process, or a“positive resist composition for solvent developing process”, as thecomponent (A), a base component (A-2) which is soluble in an alkalideveloping solution (hereafter, referred to as “component (A-2)”) may bepreferably used, and a cross-linking agent is blended. In such a resistcomposition, for example, when acid is generated from the component (B)upon exposure, the action of the acid causes cross-linking between thecomponent (A-2) and the cross-linking component. As a result, thesolubility of the resist composition in an alkali developing solution isdecreased (the solubility of the resist composition in an organicdeveloping solution is increased).

Therefore, in the formation of a resist pattern, by conducting selectiveexposure of a resist film formed by applying the resist composition to asubstrate, the exposed portions of the resist film become insoluble inan alkali developing solution (soluble in an organic developingsolution), whereas the unexposed portions of the resist film remainsoluble in an alkali developing solution (insoluble in an organicdeveloping solution), and hence, a negative resist pattern is formed byconducting development using an alkali developing solution.Alternatively, in such a case, by developing using an organic developingsolution, a positive resist pattern is formed.

As the component (A-2), a resin that is soluble in an alkali developingsolution (hereafter, referred to as “alkali-soluble resin”) ispreferably used.

Examples of the alkali soluble resin include a resin having a structuralunit derived from at least one of α-(hydroxyalkyl)acrylic acid and analkyl ester of α-(hydroxyalkyl)acrylic acid (preferably an alkyl esterhaving 1 to 5 carbon atoms), as disclosed in Japanese Unexamined PatentApplication, First Publication No. 2000-206694; an acrylic resin whichhas a sulfonamide group and may have the hydrogen atom bonded to thecarbon atom on the α-position substituted with a substituent orpolycycloolefin resin having a sulfoneamide group, as disclosed in U.S.Pat. No. 6,949,325; an acrylic resin which may have the hydrogen atombonded to the carbon atom on the α-position substituted with asubstituent and having a fluorinated alcohol, as disclosed in U.S. Pat.No. 6,949,325, Japanese Unexamined Patent Application, First PublicationNo. 2005-336452 or Japanese Unexamined Patent Application, FirstPublication No. 2006-317803; and a polycyclolefin resin having afluorinated alcohol, as disclosed in Japanese Unexamined PatentApplication, First Publication No. 2006-259582. These resins arepreferable in that a resist pattern can be formed with minimal swelling.

Here, the term “α-(hydroxyalkyl)acrylic acid” refers to one or both ofacrylic acid in which a hydrogen atom is bonded to the carbon atom onthe α-position having the carboxyl group bonded thereto, andα-hydroxyalkylacrylic acid in which a hydroxyalkyl group (preferably ahydroxyalkyl group of 1 to 5 carbon atoms) is bonded to the carbon atomon the α-position.

As the cross-linking agent, typically, an amino-based cross-linkingagent such as a glycoluril having a methylol group or alkoxymethylgroup, or a melamine-based cross-linking agent is preferable, as itenables formation of a resist pattern with minimal swelling. The amountof the cross-linker added is preferably within a range from 1 to 50parts by weight, relative to 100 parts by weight of the alkali-solubleresin.

In the case where the resist composition of the present embodiment is a“positive resist composition for alkali developing process” which formsa positive resist pattern in an alkali developing process, or a“negative resist composition for solvent developing process”, as thecomponent (A), a base component (A-1) which exhibits increased polarityby the action of acid (hereafter, referred to as “component (A-1)”) maybe preferably used. By using the component (A-1), since the polarity ofthe base component changes prior to and after exposure, an excellentdevelopment contrast can be obtained not only in an alkali developingprocess, but also in a solvent developing process.

More specifically, in the case of applying an alkali developing process,the component (A-1) is substantially insoluble in an alkali developingsolution prior to exposure, but when acid is generated from thecomponent (B) upon exposure, the action of this acid causes an increasein the polarity of the base component, thereby increasing the solubilityof the component (A-1) in an alkali developing solution. Therefore, inthe formation of a resist pattern, by conducting selective exposure of aresist film formed by applying the resist composition to a substrate,the exposed portions of the resist film change from an insoluble stateto a soluble state in an alkali developing solution, whereas theunexposed portions of the resist film remain insoluble in an alkalideveloping solution, and hence, a positive resist pattern is formed byalkali developing.

On the other hand, in the case of a solvent developing process, thecomponent (A-1) exhibits high solubility in an organic developingsolution prior to exposure, and when acid is generated from thecomponent (B) upon exposure, the polarity of the component (A-1) isincreased by the action of the generated acid, thereby decreasing thesolubility of the component (A-1) in an organic developing solution.Therefore, in the formation of a resist pattern, by conducting selectiveexposure of a resist film formed by applying the resist composition to asubstrate, the exposed portions of the resist film changes from ansoluble state to an insoluble state in an organic developing solution,whereas the unexposed portions of the resist film remain soluble in anorganic developing solution. As a result, by conducting developmentusing an organic developing solution, a contrast can be made between theexposed portions and unexposed portions, thereby forming a negativeresist pattern.

In the resist composition of the present embodiment, as the component(A), one kind of compound may be used, or two or more kinds of compoundsmay be used in combination.

In the resist composition of the present embodiment, the component (A)is preferably a component (A-1). That is, the resist composition of thepresent embodiment is preferably a resist composition which forms apositive pattern in an alkali developing process (i.e, a positive resistcompound for alkali developing process) or a resist composition whichforms a negative pattern in a solvent developing process (i.e., anegative type resist composition for solvent developing process). As thecomponent (A), at least one of a polymeric compound and a low molecularweight compound may be used.

In the case where the component (A) is a component (A-1), the component(A-1) preferably contains a resin component (A1) (hereafter, referred toas “component (A1)”).

Component (A1)

The component (A1) is a resin component preferably containing apolymeric compound having a structural unit (a1) containing an aciddecomposable group that exhibits increased polarity by the action ofacid.

The component (A1) preferably has, in addition to the structural unit(a1), a structural unit (a10) containing a hydroxystyrene skeleton.

Further, the component (A1) may have, in addition to the structural unit(a1), a structural unit (a2) containing a lactone-containing cyclicgroup, an —SO₂— containing cyclic group or a carbonate-containing cyclicgroup.

Further, the component (A1) may have, in addition to the structural unit(a1), a structural unit (a3) containing a polar group-containingaliphatic hydrocarbon group (provided that the structural units thatfall under the definition of structural units (a1) and (a2) areexcluded).

The component (A1) may further include a structural unit other than thestructural units (a1), (a2), (a3) and (a10).

<<Structural Unit (a1)>>

The structural unit (a1) is a structural unit containing an aciddecomposable group that exhibits increased polarity by the action ofacid.

The term “acid decomposable group” refers to a group in which at least apart of the bond within the structure thereof is cleaved by the actionof an acid.

Examples of acid decomposable groups which exhibit increased polarity bythe action of an acid include groups which are decomposed by the actionof an acid to form a polar group.

Examples of the polar group include a carboxy group, a hydroxy group, anamino group and a sulfo group (—SO₃H). Among these, a polar groupcontaining —OH in the structure thereof (hereafter, referred to as“OH-containing polar group”) is preferable, a carboxy group or a hydroxygroup is more preferable, and a carboxy group is particularly desirable.

More specifically, as an example of an acid decomposable group, a groupin which the aforementioned polar group has been protected with an aciddissociable group (such as a group in which the hydrogen atom of theOH-containing polar group has been protected with an acid dissociablegroup) can be given.

The “acid dissociable group” refers to both (i) a group in which thebond between the acid dissociable group and the adjacent atom is cleavedby the action of acid; and (ii) a group in which one of the bonds iscleaved by the action of acid, and then a decarboxylation reactionoccurs, thereby cleaving the bond between the acid dissociable group andthe adjacent atom.

It is necessary that the acid dissociable group that constitutes theacid decomposable group is a group which exhibits a lower polarity thanthe polar group generated by the dissociation of the acid dissociablegroup. Thus, when the acid dissociable group is dissociated by theaction of acid, a polar group exhibiting a higher polarity than that ofthe acid dissociable group is generated, thereby increasing thepolarity. As a result, the polarity of the entire component (A1) isincreased. By the increase in the polarity, the solubility in an alkalideveloping solution changes, and the solubility in an alkali developingsolution is relatively increased, whereas the solubility in an organicdeveloping solution is relatively decreased.

Examples of the acid dissociable group include groups which have beenproposed as acid dissociable groups for the base resin of a conventionalchemically amplified resist composition.

Specific examples of acid dissociable groups for the base resin of aconventional chemically amplified resist composition include“acetal-type acid dissociable group”, “tertiary alkyl ester-type aciddissociable group” and “tertiary alkyloxycarbonyl acid dissociablegroup” described below.

Acetal-Type Acid Dissociable Group

Examples of the acid dissociable group for protecting the carboxy groupor hydroxy group as a polar group include the acid dissociable grouprepresented by general formula (a1-r-1) shown below (hereafter, referredto as “acetal-type acid dissociable group”).

In the formula, Ra′¹ and Ra′² each independently represents a hydrogenatom or an alkyl group; Ra′³ represents a hydrocarbon group, providedthat Ra′³ may be bonded to Ra′¹ or Ra′² to form a ring.

In the formula (a1-r-1), it is preferable that at least one of Ra′¹ andRa′² represents a hydrogen atom, and it is more preferable that both ofRa′¹ and Ra′² represent a hydrogen atom.

In the case where Ra′¹ or Ra′² is an alkyl group, as the alkyl group,the same alkyl groups as those described above the for the substituentwhich may be bonded to the carbon atom on the α-position of theaforementioned α-substituted acrylate ester can be mentioned, and analkyl group of 1 to 5 carbon atoms is preferable. Specific examplesinclude linear or branched alkyl groups. Specific examples of the alkylgroup include a methyl group, an ethyl group, a propyl group, anisopropyl group, an n-butyl group, an isobutyl group, a tert-butylgroup, a pentyl group, an isopentyl group and a neopentyl group. Ofthese, a methyl group or an ethyl group is preferable, and a methylgroup is particularly preferable.

In formula (a1-r-1), examples of the hydrocarbon group for Ra′³ includea linear or branched alkyl group and a cyclic hydrocarbon group.

The linear alkyl group preferably has 1 to 5 carbon atoms, morepreferably 1 to 4 carbon atoms, and still more preferably 1 or 2 carbonatoms. Specific examples include a methyl group, an ethyl group, ann-propyl group, an n-butyl group and an n-pentyl group. Among these, amethyl group, an ethyl group or an n-butyl group is preferable, and amethyl group or an ethyl group is more preferable.

The branched alkyl group preferably has 3 to 10 carbon atoms, and morepreferably 3 to 5 carbon atoms. Specific examples include an isopropylgroup, an isobutyl group, a tert-butyl group, an isopentyl group, aneopentyl group a 1,1-diethylpropyl group and a 2,2-dimethylbutyl group.Among these, an isopropyl group is preferable.

In the case where Ra′³ represents a cyclic hydrocarbon group, the cyclichydrocarbon group may be an aliphatic hydrocarbon group or an aromatichydrocarbon group, and may be polycyclic or monocyclic.

As the monocyclic aliphatic hydrocarbon group, a group in which 1hydrogen atom has been removed from a monocycloalkane is preferable. Themonocycloalkane preferably has 3 to 6 carbon atoms, and specificexamples thereof include cyclopentane and cyclohexane.

As the polycyclic aliphatic hydrocarbon group, a group in which 1hydrogen atom has been removed from a polycycloalkane is preferable, andthe polycyclic group preferably has 7 to 12 carbon atoms. Examples ofthe polycycloalkane include adamantane, norbornane, isobornane,tricyclodecane and tetracyclododecane.

When the monovalent hydrocarbon group for Ra′³ is an aromatichydrocarbon group, the aromatic hydrocarbon group is a hydrocarbon grouphaving at least one aromatic ring.

The aromatic ring is not particularly limited, as long as it is a cyclicconjugated compound having (4n+2)π electrons, and may be eithermonocyclic or polycyclic. The aromatic ring preferably has 5 to 30carbon atoms, more preferably 5 to 20 carbon atoms, and still morepreferably 6 to 15 carbon atoms, and most preferably 6 to 12 carbonatoms.

Examples of the aromatic ring include aromatic hydrocarbon rings, suchas benzene, naphthalene, anthracene and phenanthrene; and aromatichetero rings in which part of the carbon atoms constituting theaforementioned aromatic hydrocarbon rings has been substituted with ahetero atom. Examples of the hetero atom within the aromatic heterorings include an oxygen atom, a sulfur atom and a nitrogen atom.Specific examples of the aromatic hetero ring include a pyridine ringand a thiophene ring.

Specific examples of the aromatic hydrocarbon group for Ra′³ include agroup in which one hydrogen atom has been removed from theaforementioned aromatic hydrocarbon ring or aromatic hetero ring (arylgroup or heteroaryl group); a group in which one hydrogen atom has beenremoved from an aromatic compound having two or more aromatic rings(biphenyl, fluorene or the like); and a group in which one hydrogen atomof the aforementioned aromatic hydrocarbon ring or aromatic hetero ringhas been substituted with an alkylene group (an arylalkyl group such asa benzyl group, a phenethyl group, a 1-naphthylmethyl group, a2-naphthylmethyl group, a 1-naphthylethyl group, or a 2-naphthylethylgroup). The alkylene group bonded to the aforementioned aromatichydrocarbon ring or the aromatic hetero ring preferably has 1 to 4carbon atoms, more preferably 1 or 2 carbon atoms, and most preferably 1carbon atom.

The cyclic hydrocarbon group for Ra′³ may have a substituent. Examplesof the substituent include —R^(P1), —R^(P2)—O—R^(P1), —R^(P2)—CO—R^(P1),—R^(P2)—CO—OR^(P1), —R^(P2)—O—CO—R^(P1), —R^(P2)—OH, —R^(P2)—CN or—R^(P2)—COOH (hereafter, these substituents are sometimes collectivelyreferred to as “Ra⁰⁵”).

Here, R^(P1) is a monovalent chain saturated hydrocarbon group having 1to 10 carbon atoms, a monovalent aliphatic cyclic saturated hydrocarbongroup having 3 to 20 carbon atoms, or a monovalent aromatic hydrocarbongroup having 6 to 30 carbon atoms. Further, R^(P2) is a single bond, adivalent chain saturated hydrocarbon group having 1 to 10 carbon atoms,a divalent aliphatic cyclic saturated hydrocarbon group having 3 to 20carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 30carbon atoms.

Here, a portion or all of the hydrogen atoms having the chain saturatedhydrocarbon group, the aliphatic cyclic saturated hydrocarbon group, andthe aromatic hydrocarbon group for R^(P1) and R^(p2) may be substitutedwith a fluorine atom. The aliphatic cyclic hydrocarbon group may have 1or more substituents of 1 kind, or 1 or more substituents of a pluralityof kinds.

Examples of the monovalent chain saturated hydrocarbon group having 1 to10 carbon atoms include a methyl group, an ethyl group, a propyl group,a butyl group, a pentyl group, a hexyl group, a heptyl group, an octylgroup, and a decyl group.

Examples of the monovalent aliphatic cyclic saturated hydrocarbon grouphaving 3 to 20 carbon atoms include a monocyclic aliphatic saturatedhydrocarbon group such as a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, a cyclodecyl group, and a cyclododecyl group; and a polycyclicaliphatic saturated hydrocarbon group such as a bicyclo[2.2.2]octanylgroup, a tricyclo[5.2.1.02,6]decanyl group, atricyclo[3.3.1.13,7]decanyl group, atetracyclo[6.2.1.13,6.02,7]dodecanyl group, and an adamantyl group.

Examples of the monovalent aromatic hydrocarbon group having 6 to 30carbon atoms include a group obtained by removing one hydrogen atom fromthe aromatic hydrocarbon ring such as benzene, biphenyl, fluorene,naphthalene, anthracene, and phenanthrene.

In the case where Ra′³ is bonded to Ra′¹ or Ra′² to form a ring, thecyclic group is preferably a 4 to 7-membered ring, and more preferably a4 to 6-membered ring. Specific examples of the cyclic group includetetrahydropyranyl group and tetrahydrofuranyl group.

Tertiary Alkyl Ester-Type Acid Dissociable Group

Examples of the acid dissociable group for protecting the carboxy groupas a polar group include the acid dissociable group represented bygeneral formula (a1-r-2) shown below.

Among the acid dissociable groups represented by general formula(a1-r-2), for convenience, a group which is constituted of alkyl groupsis referred to as “tertiary ester-type acid dissociable group”.

In the formula, Ra′⁴ to Ra′⁶ each independently represents a hydrocarbongroup, provided that Ra′⁵ and Ra′⁶ may be mutually bonded to form aring.

Examples of the hydrocarbon group for Ra′⁴ include a linear or branchedalkyl group, a chain or cyclic alkenyl group, and a cyclic hydrocarbongroup.

The linear or branched alkyl group and the cyclic hydrocarbon group(monocyclic aliphatic hydrocarbon group, polycyclic aliphatichydrocarbon group or aromatic hydrocarbon group) for Ra′⁴ are the sameas defined for Ra′³.

The chain or cyclic alkenyl group for Ra′⁴ is preferably an alkenylgroup having 2 to 10 carbon atoms.

The hydrocarbon group for Ra′⁵ and Ra′⁶ is the same as defined for Ra′³.

In the case where Ra′⁵ and Ra′⁶ are mutually bonded to form a ring, agroup represented by general formula (a1-r2-1) shown below, a grouprepresented by general formula (a1-r2-2) shown below, and a grouprepresented by general formula (a1-r2-3) shown below may be given aspreferable examples.

On the other hand, in the case where Ra′⁴ to Ra′⁶ are not mutuallybonded and independently represent a hydrocarbon group, the grouprepresented by general formula (a1-r2-4) shown below may be given as apreferable example.

In formula (a1-r2-1), Ra′¹⁰ represents an alkyl group of 1 to 10 carbonatoms, or a group represented by general formula (a1-r2-r1) shown below;Ra′¹¹ is a group which forms an aliphatic cyclic group together with acarbon atom having Ra′¹⁰ bonded thereto. In formula (a1-r2-2), Yarepresents a carbon atom; Xa represents a group which forms a cyclichydrocarbon group together with Ya, provided that part or all of thehydrogen atoms of the cyclic hydrocarbon group may be substituted; Ra⁰¹to Ra⁰³ each independently represents a hydrogen atom, a monovalentsaturated chain hydrocarbon group of 1 to 10 carbon atoms or amonovalent saturated aliphatic cyclic hydrocarbon group of 3 to 20carbon atoms, provided that part or all of the hydrogen atoms of thesaturated chain hydrocarbon or the saturated aliphatic cyclichydrocarbon may be substituted; two or more of Ra⁰¹ to Ra⁰³ may bemutually bonded to form a cyclic structure. In formula (a1-r2-3), Yaarepresents a carbon atom; Xaa represents a group which forms analiphatic cyclic group together with Yaa; Ra⁰⁴ represents an aromatichydrocarbon group which may have a substituent. In formula (a1-r2-4),Ra′¹² and Ra′¹³ each independently represents a hydrogen atom or amonovalent saturated hydrocarbon group of 1 to 10 carbon atoms, providedthat part or all of the hydrogen atoms of the saturated hydrocarbongroup may be substituted; Ra′¹⁴ represents a hydrocarbon group which mayhave a substituent; and * represents a valence bond (the same definitionhereafter).

In the formula, Ya⁰ represents a quaternary carbon atom; Ra⁰³¹, Ra⁰³²and Ra⁰³³ each independently represents a hydrocarbon group which mayhave a substituent; provided that at least one Ra⁰³¹, Ra⁰³² and Ra⁰³³ isa hydrocarbon group having a polar group.

In the formula (a1-r2-1), as the alkyl group of 1 to 10 carbon atoms forRa′10, the same groups as described above for the linear or branchedalkyl group for Ra′³ in the formula (a1-r-1) are preferable. Ra′¹⁰ ispreferably an alkyl group of 1 to 5 carbon atoms.

In formula (a1-r2-r1), Ya⁰ represents a quaternary carbon atom. That is,the number of carbon atoms bonded to Ya⁰ (carbon atom) is 4.

In formula (a1-r2-r1), Ra⁰³¹, Ra⁰³² and Ra⁰³³ each independentlyrepresents a hydrocarbon group which may have a substituent. Examples ofthe hydrocarbon group for Ra⁰³¹, Ra⁰³² and Ra⁰³³ include a linear orbranched alkyl group, a chain or cyclic alkenyl group, and a cyclichydrocarbon group.

The linear alkyl group for Ra⁰³¹, Ra⁰³² and Ra⁰³³ preferably has 1 to 5carbon atoms, more preferably 1 to 4 carbon atoms, and still morepreferably 1 or 2 carbon atoms. Specific examples include a methylgroup, an ethyl group, an n-propyl group, an n-butyl group and ann-pentyl group. Among these, a methyl group, an ethyl group or ann-butyl group is preferable, and a methyl group or an ethyl group ismore preferable.

The branched alkyl group for Ra⁰³¹, Ra⁰³² and Ra⁰³³ preferably has 3 to10 carbon atoms, and more preferably 3 to 5 carbon atoms. Specificexamples include an isopropyl group, an isobutyl group, a tert-butylgroup, an isopentyl group, a neopentyl group a 1,1-diethylpropyl groupand a 2,2-dimethylbutyl group. Among these, an isopropyl group ispreferable.

The chain or cyclic alkenyl group for Ra⁰³¹, Ra⁰³² and Ra⁰³³ ispreferably an alkenyl group having 2 to 10 carbon atoms.

The cyclic hydrocarbon group for Ra⁰³¹, Ra⁰³² and Ra⁰³³ may be analiphatic hydrocarbon group or an aromatic hydrocarbon group, and may bepolycyclic or monocyclic.

As the monocyclic aliphatic hydrocarbon group, a group in which 1hydrogen atom has been removed from a monocycloalkane is preferable. Themonocycloalkane preferably has 3 to 6 carbon atoms, and specificexamples thereof include cyclopentane and cyclohexane.

As the polycyclic aliphatic hydrocarbon group, a group in which 1hydrogen atom has been removed from a polycycloalkane is preferable, andthe polycyclic group preferably has 7 to 12 carbon atoms. Examples ofthe polycycloalkane include adamantane, norbornane, isobornane,tricyclodecane and tetracyclododecane.

The aromatic hydrocarbon group for Ra⁰³¹, Ra⁰³² and Ra⁰³³ is ahydrocarbon group having at least one aromatic ring. The aromatic ringis not particularly limited, as long as it is a cyclic conjugatedcompound having (4n+2) R electrons, and may be either monocyclic orpolycyclic. The aromatic ring preferably has 5 to 30 carbon atoms, morepreferably 5 to 20, still more preferably 6 to 15, and most preferably 6to 12. Examples of the aromatic ring include aromatic hydrocarbon rings,such as benzene, naphthalene, anthracene and phenanthrene; and aromatichetero rings in which part of the carbon atoms constituting theaforementioned aromatic hydrocarbon rings has been substituted with ahetero atom. Examples of the hetero atom within the aromatic heterorings include an oxygen atom, a sulfur atom and a nitrogen atom.Specific examples of the aromatic hetero ring include a pyridine ringand a thiophene ring. Specific examples of the aromatic hydrocarbongroup include a group in which one hydrogen atom has been removed fromthe aforementioned aromatic hydrocarbon ring or aromatic hetero ring(aryl group or heteroaryl group); a group in which one hydrogen atom hasbeen removed from an aromatic compound having two or more aromatic rings(biphenyl, fluorene or the like); and a group in which one hydrogen atomof the aforementioned aromatic hydrocarbon ring or aromatic hetero ringhas been substituted with an alkylene group (an arylalkyl group such asa benzyl group, a phenethyl group, a 1-naphthylmethyl group, a2-naphthylmethyl group, a 1-naphthylethyl group, or a 2-naphthylethylgroup). The alkylene group bonded to the aforementioned aromatichydrocarbon ring or the aromatic hetero ring preferably has 1 to 4carbon atoms, more preferably 1 or 2 carbon atoms, and most preferably 1carbon atom.

In the case where the hydrocarbon group for Ra⁰³¹, Ra⁰³² and Ra⁰³³ issubstituted, examples of the substituent include a hydroxy group, acarboxy group, a halogen atom (such as a fluorine atom, a chlorine atomor a chlorine atom), an alkoxy group (such as a methoxy group, an ethoxygroup, a propoxy group or a butoxy group), and an alkyloxycarbonylgroup.

Among these examples, as the hydrocarbon group (which may have asubstituent) for Ra⁰³¹, Ra⁰³² and Ra⁰³³, a linear or branched alkylgroup which may have a substituent is preferable, and a linear alkylgroup is more preferable.

However, at least one of Ra⁰³¹, Ra⁰³² and Ra⁰³³ is a hydrocarbon grouphaving a polar group.

The “hydrocarbon group having a polar group” includes a group in which amethylene group (—CH₂—)constituting the hydrocarbon group is substitutedwith a polar group, and a group in which at least one hydrogen atomconstituting the hydrocarbon group has been substituted with a polargroup.

Examples of the “hydrocarbon group having a polar group” include afunctional group represented by general formula (a1-p1) shown below.

In the formula, Ra⁰⁷ represents a divalent hydrocarbon group having 2 to12 carbon atoms; Ra⁰⁸ represents a divalent linking group containing ahetero atom; Ra⁰⁶ represents a monovalent hydrocarbon group having 1 to12 carbon atoms;

and n_(p0) represents an integer of 1 to 6.

In formula (a1-p1), Ra⁰⁷ represents a divalent hydrocarbon group having2 to 12 carbon atoms.

Ra⁰⁷ has 2 to 12 carbon atoms, preferably 2 to 8 carbon atoms, morepreferably 2 to 6 carbon atoms, still more preferably 2 to 4 carbonatoms, and most preferably 2 carbon atoms.

The hydrocarbon group for Ra⁰⁷ is preferably a chain or cyclic aliphatichydrocarbon group, and more preferably a chain hydrocarbon group.

Examples of Ra⁰⁷ include a linear alkanediyl group, such as an ethylenegroup, a propane-1,3-diyl group, butane-1,4-diyl group, apentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diylgroup, an octane-1,8-diyl group, a nonane-1,9-diyl group, adecane-1,10-diyl group, an undecane-1,11-diyl group, and adodecane-1,12-diyl group; a branched alkanediyl group, such as apropane-1,2-diyl group, a 1-methylbutane-1,3-diyl group, a2-methylpropane-1,3-diyl group, a pentane-1,4-diyl group, and a2-methylbutane-1,4-diyl group; a cycloalkanediyl group, such as acyclobutane-1,3-diyl group, a cyclopentane-1,3-diyl group, acyclohexane-1,4-diyl group, and a cyclooctane-1,5-diyl group; and apolycyclic divalent alicyclic hydrocarbon group, such as anorbornane-1,4-diyl group, a norbornane-2,5-diyl group, anadamantane-1,5-diyl group, and an adamantane-2,6-diyl group.

Among these examples, an alkanediyl group is preferable, and a linearalkanediyl group is more preferable.

In formula (a1-p1), Ra⁰⁸ represents a divalent linking group containinga hetero atom.

Examples of Ra⁰⁸ include —O—, —C(═O)—O—, —C(═O)—, —O—C(═O)—O—,—C(═O)—NH—, —NH—, −NH—C(═NH)— (H may be substituted with a substituentsuch as an alkyl group or an acyl group), —S—, —S(═O)₂—, and —S(═O)₂—O—.

Among these examples, in terms of solubility in a developing solution,—O—, —C(═O)—O—, —C(═O)—, or —O—C(═O)—O— are preferable, and —O— or—C(═O)— is most preferable.

In formula (a1-p1), Ra⁰⁶ represents a monovalent hydrocarbon grouphaving 1 to 12 carbon atoms.

Ra⁰⁶ has 1 to 12 carbon atoms. In terms of solubility in a developingsolution, Ra⁰⁶ preferably has 1 to 8 carbon atoms, more preferably 1 to5 carbon atoms, still more preferably 1 to 3 carbon atoms, still morepreferably 1 or 2 carbon atoms, and most preferably 1 carbon atoms.

Examples of the hydrocarbon group for Ra⁰⁶ include a chain hydrocarbongroup, a cyclic hydrocarbon group, and a combination of a chainhydrocarbon group and a cyclic hydrocarbon group.

Examples of the chain hydrocarbon group include a methyl group, an ethylgroup, an n-propyl group, an isopropyl group, an n-butyl group, asec-butyl group, a tert-butyl group, an n-pentyl group, an n-hexylgroup, an n-heptyl group, a 2-ethylhexyl group, an n-octyl group, ann-nonyl group, an n-decyl group, an n-undecyl group and an n-dodecylgroup.

The cyclic hydrocarbon group may be an alicyclic hydrocarbon group or anaromatic hydrocarbon group.

The alicyclic hydrocarbon group may be monocyclic or polycyclic.Examples of monocyclic alicyclic hydrocarbon groups include cycloalkylgroups, such as a cyclopropyl group, a cyclobutyl group, a cyclopentylgroup, a cyclohexyl group, a dimethylcyclohexyl group, a cycloheptylgroup, a cyclooctyl group, a cycloheptyl group, and a cyclodecyl group.Examples of polycyclic alicyclic hydrocarbon groups include adecahydronaphthyl group, an adamantyl group, a 2-alkyladamantan-2-ylgroup, a 1-(adamantan-1-yl)alkan-1-yl group, a norbornyl group, amethylnorbornyl group, and an isonorbornyl group.

Examples of aromatic hydrocarbon groups include a phenyl group, anaphthyl group, an anthryl group, a p-methylphenyl group, ap-tert-butylphenyl group, a p-adamantylphenyl group, a tolyl group, axylyl group, a cumenyl group, a mesityl group, a biphenyl group, aphenanthryl group, 2,6-diethylphenyl group, and 2-methyl-6-ethyl phenylgroup.

In terms of solubility in a developing solution, Ra⁰⁶ is preferably achain hydrocarbon group, more preferably an alkyl group, and still morepreferably a linear alkyl group.

In formula (a1-p1), n_(p0) is an integer of 1 to 6, preferably aninteger of 1 to 3, more preferably 1 or 2, and still more preferably 1.

Specific examples of the hydrocarbon group having a polar group areshown below.

In the following formulae, * represents a valence bond which is bondedto the quaternary carbon atom (Ya⁰).

In formula (a1-r2-r1), at least one of Ra⁰³¹, Ra⁰³² and Ra⁰³³ is ahydrocarbon group having a polar group. However, the number ofhydrocarbon groups having a polar group may be appropriately selecteddepending on the solubility in the developing solution used in theformation of a resist pattern. For example, it is preferable that one ortwo of Ra⁰³¹, Ra⁰³² and Ra⁰³³ is a hydrocarbon group having a polargroup, and it is more preferable that one of Ra⁰³¹, Ra⁰³² and Ra⁰³³ ishydrocarbon group having a polar group.

The hydrocarbon group having a polar group may have a substituent otherthan a polar group.

Examples of such substituent include a halogen atom (such as a fluorineatom, a chlorine atom or a bromine atom), and a halogenated alkyl grouphaving 1 to 5 carbon atoms.

In formula (a1-r2-1), the aliphatic cyclic group which is formed byRa′¹¹ together with the carbon atom bonded to Ra′¹⁰, the same groups asthose described above for the monocyclic or polycyclic aliphatichydrocarbon group for Ra′³ in formula (a1-r-1) are preferable.

In formula (a1-r2-2), as the cyclic hydrocarbon group formed by Xatogether with Ya, a group in which 1 or more hydrogen atoms have beenremoved from the monovalent cyclic hydrocarbon group (aliphatichydrocarbon group) for Ra′³ in the aforementioned formula (a1-r-1) maybe mentioned.

The cyclic hydrocarbon group which Xa forms with Ya may have asubstituent. Examples of substituents include the same substituents asthose which the cyclic hydrocarbon group for Ra′³ may have.

In formula (a1-r2-2), examples of the monovalent saturated chainhydrocarbon group of 1 to 10 carbon atoms for Ra⁰¹ to Ra⁰³ include amethyl group, an ethyl group, a propyl group, a butyl group, a pentylgroup, a hexyl group, a heptyl group, an octyl group, and a decyl group.

Examples of the monovalent aliphatic cyclic saturated hydrocarbon grouphaving 3 to 20 carbon atoms for Ra⁰¹ to Ra⁰³ include a monocyclicaliphatic saturated hydrocarbon group such as a cyclopropyl group, acyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptylgroup, a cyclooctyl group, a cyclodecyl group, and a cyclododecyl group;and a polycyclic aliphatic saturated hydrocarbon group such as abicyclo[2.2.2]octanyl group, a tricyclo[5.2.1.02,6]decanyl group, atricyclo[3.3.1.13,7]decanyl group, atetracyclo[6.2.1.13,6.02,7]dodecanyl group, and an adamantyl group.

Among these examples, as Ra⁰¹ to Ra⁰³, in terms of ease in synthesis ofthe monomeric compound which derives the structural unit (a1), ahydrogen atom or a saturated chain hydrocarbon group having 1 to 10carbon atoms is preferable, a hydrogen atom, a methyl group or an ethylgroup is more preferable, and a hydrogen atom is most preferable.

As the substituent for the saturated chain hydrocarbon group orsaturated cyclic aliphatic hydrocarbon group represented by Ra⁰¹ toRa⁰³, for example, the same substituents as those described above forRa⁰⁵ may be mentioned.

Examples of the group containing a carbon-carbon double bond which isgenerated by forming a cyclic structure in which two or more of Ra⁰¹ toRa⁰³ are bonded to each other include a cyclopentenyl group, acyclohexenyl group, a methyl cyclopentenyl group, a methyl cyclohexenylgroup, a cyclopentylideneethenyl group, and a cyclohexylidenethenylgroup. Among these examples, from the viewpoint of the ease of synthesisof the monomer compound which derives the structural unit (a1), acyclopentenyl group, a cyclohexenyl group, and a cyclopentylidenethenylgroup are preferable.

In formula (a1-r2-3), an aliphatic cyclic group which is formed of Xaatogether with Yaa is preferably a group exemplified as an aliphatichydrocarbon group which is a monocyclic group or a polycyclic group ofRa′³ in general formula (a1-r-1). In general formula (a1-r2-3), examplesof the aromatic hydrocarbon group for Ra⁴ include a group obtained byremoving one or more hydrogen atoms from an aromatic hydrocarbon ringhaving 5 to 30 carbon atoms. Among these examples, Ra⁴ is preferably agroup obtained by removing one or more hydrogen atoms from an aromatichydrocarbon ring having 6 to 15 carbon atoms, a group obtained byremoving one or more hydrogen atoms from benzene, naphthalene,anthracene, or phenanthrene is further preferable, a group obtained byremoving one or more hydrogen atoms from benzene, naphthalene, oranthracene is still further preferable, a group obtained by removing oneor more hydrogen atoms from benzene and naphthalene is particularlypreferable, and a group obtained by removing one or more hydrogen atomsfrom benzene is most preferable.

Examples of the substituent that Ra⁴ in general formula (a1-r2-3) mayhave include a methyl group, an ethyl group, a propyl group, a hydroxylgroup, a carboxyl group, a halogen atom (a fluorine atom, a chlorineatom, a bromine atom, or the like), an alkoxy group (a methoxy group, anethoxy group, a propoxy group, a butoxy group, or the like), and analkyloxycarbonyl group.

In general formula (a1-r2-4), Ra′¹² and Ra′¹³ each independentlyrepresent a monovalent chain saturated hydrocarbon group having 1 to 10carbon atoms or a hydrogen atom. With respect to Ra′¹² and Ra′¹³,examples of the monovalent chain saturated hydrocarbon group having 1 to10 carbon atoms include the same monovalent chain saturated hydrocarbongroup having 1 to 10 carbon atoms as that for Ra⁰¹ to Ra⁰³ provided thatpart or all of the hydrogen atoms of the saturated hydrocarbon group maybe substituted;

Among these examples, as Ra′¹² and Ra′¹³, a hydrogen atom and an alkylgroup having 1 to 5 carbon atoms are preferable, an alkyl group having 1to 5 carbon atoms is further preferable, a methyl group and an ethylgroup are still further preferable, and a methyl group is particularlypreferable.

In the case where the chain saturated hydrocarbon group represented byRa′¹² and Ra′¹³ is substituted, examples of the substituent include thesame group as that of Ra⁰⁵.

In general formula (a1-r2-4), Ra′¹⁴ is a hydrocarbon group which mayhave a substituent. Examples of the hydrocarbon group for Ra′¹⁴ includea linear or branched alkyl group and a cyclic hydrocarbon group.

The linear alkyl group for Ra′¹⁴ preferably has 1 to 5 carbon atoms,more preferably 1 to 4 carbon atoms, and still more preferably 1 or 2carbon atoms. Specific examples include a methyl group, an ethyl group,an n-propyl group, an n-butyl group and an n-pentyl group. Among these,a methyl group, an ethyl group or an n-butyl group is preferable, and amethyl group or an ethyl group is more preferable.

The branched alkyl group for Ra′¹⁴ preferably has 3 to 10 carbon atoms,and more preferably 3 to 5 carbon atoms. Specific examples include anisopropyl group, an isobutyl group, a tert-butyl group, an isopentylgroup, a neopentyl group a 1,1-diethylpropyl group and a2,2-dimethylbutyl group. Among these, an isopropyl group is preferable.

In the case where Ra′¹⁴ represents a cyclic hydrocarbon group, thecyclic hydrocarbon group may be an aliphatic hydrocarbon group or anaromatic hydrocarbon group, and may be polycyclic or monocyclic.

As the monocyclic aliphatic hydrocarbon group, a group in which 1hydrogen atom has been removed from a monocycloalkane is preferable. Themonocycloalkane preferably has 3 to 6 carbon atoms, and specificexamples thereof include cyclopentane and cyclohexane.

As the polycyclic aliphatic hydrocarbon group, a group in which 1hydrogen atom has been removed from a polycycloalkane is preferable, andthe polycyclic group preferably has 7 to 12 carbon atoms. Examples ofthe polycycloalkane include adamantane, norbornane, isobornane,tricyclodecane and tetracyclododecane.

Examples of the aromatic hydrocarbon group for Ra′¹⁴ include the samearomatic hydrocarbon groups as those described above for Ra⁴. Amongthese examples, Ra′¹⁴ is preferably a group formed by removing one ormore hydrogen atoms from an aromatic hydrocarbon ring having 6 to 15carbon atoms, more preferably a group formed by removing one or morehydrogen atoms from benzene, naphthalene, anthracene, or phenanthrene,still more preferably a group formed by removing one or more hydrogenatoms from benzene, naphthalene, or anthracene, still more preferably agroup formed by removing one or more hydrogen atoms from naphthalene oranthracene, and most preferably a group formed by removing one or morehydrogen atoms from naphthalene.

Examples of the substituent that Ra′¹⁴ may have include the same groupas the substituent that Ra⁴ may have.

In the case where Ra′¹⁴ in general formula (a1-r2-4) is a naphthylgroup, a position which is bonded to a tertiary carbon atom in generalformula (a1-r2-4) may be 1-position and 2-position of the naphthylgroup.

In the case where Ra′¹⁴ in general formula (a1-r2-4) is an anthrylgroup, a position which is bonded to a tertiary carbon atom in generalformula (a1-r2-4) may be any one of 1-position, 2-position, and9-position of the anthryl group.

Specific examples of the group represented by the aforementioned formula(a1-r2-1) are shown below.

Specific examples of the group represented by the aforementioned formula(a1-r2-2) are shown below.

Specific examples of the group represented by the aforementioned formula(a1-r2-3) are shown below.

Specific examples of the group represented by the aforementioned formula(a1-r2-4) are shown below.

Tertiary Alkyloxycarbonyl Acid Dissociable Group

Examples of the acid dissociable group for protecting a hydroxy group asa polar group include the acid dissociable group represented by generalformula (a1-r-3) shown below (hereafter, for convenience, referred to as“tertiary alkyloxycarbonyl-type acid dissociable group”).

In the formula, Ra′⁷ to Ra′⁹ each independently represents an alkylgroup.

In formula (a1-r-3), each of Ra′⁷ to Ra′⁹ is preferably an alkyl grouphaving 1 to 5 carbon atoms, and more preferably an alkyl group having 1to 3 carbon atoms. Further, the total number of carbon atoms in thealkyl groups is preferably 3 to 7, more preferably 3 to 5, and stillmore preferably 3 or 4.

Examples of the structural unit (a1) include a structural unit derivedfrom an acrylate ester which may have the hydrogen atom bonded to thecarbon atom on the α-position substituted with a substituent; astructural unit derived from an acrylamide; a structural unit derivedfrom hydroxystyrene or a hydroxystyrene derivative in which at least apart of the hydrogen atom of the hydroxy group is protected with asubstituent containing an acid decomposable group; and a structural unitderived from vinylbenzoic acid or a vinylbenzoic acid derivative inwhich at least a part of the hydrogen atom within —C(═O)—OH is protectedwith a substituent containing an acid decomposable group.

As the structural unit (a1), a structural unit derived from an acrylateester which may have the hydrogen atom bonded to the carbon atom on theα-position substituted with a substituent is preferable.

Specific examples of preferable structural units for the structural unit(a1) include structural units represented by general formula (a1-1) or(a1-2) shown below.

In the formula, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms; Va¹represents a divalent hydrocarbon group optionally having an ether bond;n_(a1) represents an integer of 0 to 2; Ra¹ represents an aciddissociable group represented by the aforementioned formula (a1-r-1) or(a1-r-2); Wa¹ represents a hydrocarbon group having a valency ofn_(a2)+1; n_(a2) represents an integer of 1 to 3; and Ra² represents anacid dissociable group represented by the aforementioned general formula(a1-r-1) or (a1-r-3).

In the aforementioned formula (a1-1), as the alkyl group of 1 to 5carbon atoms for R, a linear or branched alkyl group of 1 to 5 carbonatoms is preferable, and specific examples thereof include a methylgroup, an ethyl group, a propyl group, an isopropyl group, an n-butylgroup, an isobutyl group, a tert-butyl group, a pentyl group, anisopentyl group and a neopentyl group. The halogenated alkyl group of 1to 5 carbon atoms represented by R is a group in which part or all ofthe hydrogen atoms of the aforementioned alkyl group of 1 to 5 carbonatoms have been substituted with halogen atoms. Examples of the halogenatom include a fluorine atom, a chlorine atom, a bromine atom and aniodine atom, and a fluorine atom is particularly desirable.

As R, a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or afluorinated alkyl group of 1 to 5 carbon atoms is preferable, and ahydrogen atom or a methyl group is particularly desirable in terms ofindustrial availability.

In formula (a1-1), the divalent hydrocarbon group for V¹ may be eitheran aliphatic hydrocarbon group or an aromatic hydrocarbon group.

The aliphatic hydrocarbon group as the divalent hydrocarbon group forVa¹ may be either saturated or unsaturated. In general, the aliphatichydrocarbon group is preferably saturated.

As specific examples of the aliphatic hydrocarbon group, a linear orbranched aliphatic hydrocarbon group, and an aliphatic hydrocarbon groupcontaining a ring in the structure thereof can be given.

The linear aliphatic hydrocarbon group preferably has 1 to 10 carbonatoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4carbon atoms, and most preferably 1 to 3 carbon atoms.

As the linear aliphatic hydrocarbon group, a linear alkylene group ispreferable. Specific examples thereof include a methylene group [—CH₂—],an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], atetramethylene group [—(CH₂)₄—] and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group preferably has 2 to 10 carbonatoms, more preferably 3 to 6, still more preferably 3 or 4, and mostpreferably 3.

As the branched aliphatic hydrocarbon group, branched alkylene groupsare preferred, and specific examples include various alkylalkylenegroups, including alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—,—C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—;alkylethylene groups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—,—C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylenegroups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; andalkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and—CH₂CH(CH₃)CH₂CH₂—. As the alkyl group within the alkylalkylene group, alinear alkyl group of 1 to 5 carbon atoms is preferable.

As examples of the hydrocarbon group containing a ring in the structurethereof, an alicyclic hydrocarbon group (a group in which two hydrogenatoms have been removed from an aliphatic hydrocarbon ring), a group inwhich the alicyclic hydrocarbon group is bonded to the terminal of theaforementioned chain-like aliphatic hydrocarbon group, and a group inwhich the alicyclic group is interposed within the aforementioned linearor branched aliphatic hydrocarbon group, can be given. The linear orbranched aliphatic hydrocarbon group is the same as defined for theaforementioned linear aliphatic hydrocarbon group or the aforementionedbranched aliphatic hydrocarbon group.

The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, andmore preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be either a monocyclic group or apolycyclic group. As the monocyclic aliphatic hydrocarbon group, a groupin which 2 hydrogen atoms have been removed from a monocycloalkane ispreferable. The monocycloalkane preferably has 3 to 6 carbon atoms, andspecific examples thereof include cyclopentane and cyclohexane. As thepolycyclic group, a group in which two hydrogen atoms have been removedfrom a polycycloalkane is preferable, and the polycyclic grouppreferably has 7 to 12 carbon atoms. Examples of the polycycloalkaneinclude adamantane, norbornane, isobornane, tricyclodecane andtetracyclododecane.

The aromatic hydrocarbon group as the divalent hydrocarbon group for Va¹is a hydrocarbon group having an aromatic ring.

The aromatic hydrocarbon group preferably has 3 to 30 carbon atoms, morepreferably 5 to 30, still more preferably 5 to 20, still more preferably6 to 15, and most preferably 6 to 12. Here, the number of carbon atomswithin a substituent(s) is not included in the number of carbon atoms ofthe aromatic hydrocarbon group.

Examples of the aromatic ring contained in the aromatic hydrocarbongroup include aromatic hydrocarbon rings, such as benzene, biphenyl,fluorene, naphthalene, anthracene and phenanthrene; and aromatic heterorings in which part of the carbon atoms constituting the aforementionedaromatic hydrocarbon rings has been substituted with a hetero atom.Examples of the hetero atom within the aromatic hetero rings include anoxygen atom, a sulfur atom and a nitrogen atom.

Specific examples of the aromatic hydrocarbon group include a group inwhich two hydrogen atoms have been removed from the aforementionedaromatic hydrocarbon ring (arylene group); and a group in which onehydrogen atom has been removed from the aforementioned aromatichydrocarbon ring (aryl group) and one hydrogen atom has been substitutedwith an alkylene group (such as a benzyl group, a phenethyl group, a1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethylgroup, or a 2-naphthylethyl group). The alkylene group (alkyl chainwithin the arylalkyl group) preferably has 1 to 4 carbon atom, morepreferably 1 or 2, and most preferably 1.

In formula (a1-1), Ra¹ represents an acid dissociable group representedby the aforementioned formula (a1-r-1) or (a1-r-2).

In the aforementioned formula (a1-2), the hydrocarbon group for Wa¹having a valency of n_(a2)+1 may be either an aliphatic hydrocarbongroup or an aromatic hydrocarbon group. The aliphatic cyclic grouprefers to a hydrocarbon group that has no aromaticity, and may be eithersaturated or unsaturated, but is preferably saturated. Examples of thealiphatic hydrocarbon group include a linear or branched aliphatichydrocarbon group, an aliphatic hydrocarbon group containing a ring inthe structure thereof, and a combination of the linear or branchedaliphatic hydrocarbon group and the aliphatic hydrocarbon groupcontaining a ring in the structure thereof.

The valency of na₂+1 is preferably divalent, trivalent or tetravalent,and divalent or trivalent is more preferable.

In formula (a1-2), Ra² represents an acid dissociable group representedby the aforementioned formula (a1-r-1) or (a1-r-3).

Specific examples of structural unit represented by formula (a1-1) areshown below. In the formulae shown below, Ra represents a hydrogen atom,a methyl group or a trifluoromethyl group.

Specific examples of structural unit represented by formula (a1-2) areshown below.

As the structural unit (a1) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

From the viewpoint that the properties of the lithography (sensitivity,shape, and the like) by electron beam and EUV are more likely to beenhanced, the structural unit (a1) is further preferably a structuralunit represented by general formula (a1-1).

Among these examples, as the structural unit (a1), a structural unitrepresented by general formula (a1-1-1) is particularly preferable.

In the formula, Ra¹″ is an acid dissociable group represented by generalformula (a1-r2-1), (a1-r2-3), or (a1-r2-4).

In general formula (a1-1-1), R, Va¹ and n_(a1) are the same as definedfor R, Va¹ and n_(a1) in general formula (a1-1).

The description of the acid dissociable group represented by generalformula (a1-r2-1), (a1-r2-3), or (a1-r2-4) is the same as describedabove.

In the component (A1), the amount of the structural unit (a1) based onthe combined total (100 mol %) of all structural units constituting thecomponent (A1) is preferably 5 to 80 mol %, more preferably 10 to 75 mol%, and still more preferably 30 to 70 mol %.

When the amount of the structural unit (a1) is at least as large as thelower limit of the above-mentioned range, various lithography propertiessuch as sensitivity, resolution and roughness may be improved. On theother hand, when the amount of the structural unit (a1) is no more thanthe upper limit of the above-mentioned range, a good balance may beachieved with the other structural units, and the lithography propertiesmay be improved.

<<Structural Unit (a10) Containing Hydroxystyrene Skeleton>>

The component (A1) preferably has, in addition to the structural unit(a1), a structural unit (a10) containing a hydroxystyrene skeleton.

Preferable examples of the structural unit (a10) include a structuralunit represented by general formula (a10-1) shown below.

In the formula, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms;Ya^(x1) represents a single bond or a divalent linking group; Wa^(x1)represents an aromatic hydrocarbon group having a valency of(n_(ax1)+1); and n_(ax1) represents an integer of 1 to 3.

In general formula (a10-1), R represents a hydrogen atom, an alkyl groupof 1 to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbonatoms.

As the alkyl group of 1 to 5 carbon atoms for R, a linear or branchedalkyl group of 1 to 5 carbon atoms is preferable, and specific examplesthereof include a methyl group, an ethyl group, a propyl group, anisopropyl group, an n-butyl group, an isobutyl group, a tert-butylgroup, a pentyl group, an isopentyl group and a neopentyl group. Thehalogenated alkyl group of 1 to 5 carbon atoms represented by R is agroup in which part or all of the hydrogen atoms of the aforementionedalkyl group of 1 to 5 carbon atoms have been substituted with halogenatoms. Examples of the halogen atom include a fluorine atom, a chlorineatom, a bromine atom and an iodine atom, and a fluorine atom isparticularly desirable.

As R, a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or afluorinated alkyl group of 1 to 5 carbon atoms is preferable, and ahydrogen atom or a methyl group is particularly desirable in terms ofindustrial availability.

In formula (a10-1), Ya^(x1) represents a single bond or a divalentlinking group.

Preferable examples of the divalent linking group for Ya^(x1) include adivalent hydrocarbon group which may have a substituent, and a divalentlinking group containing a hetero atom.

Divalent Hydrocarbon Group which May have a Substituent:

In the case where Ya^(x1) is a divalent linking group which may have asubstituent, the hydrocarbon group may be either an aliphatichydrocarbon group or an aromatic hydrocarbon group.

Aliphatic Hydrocarbon Group for Ya^(x1)

The “aliphatic hydrocarbon group” refers to a hydrocarbon group that hasno aromaticity. The aliphatic hydrocarbon group may be saturated orunsaturated. In general, the aliphatic hydrocarbon group is preferablysaturated.

Examples of the aliphatic hydrocarbon group include a linear or branchedaliphatic hydrocarbon group, and an aliphatic hydrocarbon groupcontaining a ring in the structure thereof can be given.

Linear or Branched Aliphatic Hydrocarbon Group

The linear aliphatic hydrocarbon group preferably has 1 to 10 carbonatoms, more preferably 1 to 6, still more preferably 1 to 4, and mostpreferably 1 to 3.

As the linear aliphatic hydrocarbon group, a linear alkylene group ispreferable. Specific examples thereof include a methylene group [—CH₂—],an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], atetramethylene group [—(CH₂)₄—] and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group preferably has 2 to 10 carbonatoms, more preferably 3 to 6, still more preferably 3 or 4, and mostpreferably 3. As the branched aliphatic hydrocarbon group, branchedalkylene groups are preferred, and specific examples include variousalkylalkylene groups, including alkylmethylene groups such as —CH(CH₃)—,—CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and—C(CH₂CH₃)₂—; alkylethylene groups such as —CH(CH₃)CH₂—,—CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—;alkyltrimethylene groups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—;and alkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and—CH₂CH(CH₃)CH₂CH₂—. As the alkyl group within the alkylalkylene group, alinear alkyl group of 1 to 5 carbon atoms is preferable.

The linear or branched aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include a fluorine atom, afluorinated alkyl group of 1 to 5 carbon atoms, and a carbonyl group.

Aliphatic Hydrocarbon Group Containing a Ring in the Structure Thereof

As examples of the hydrocarbon group containing a ring in the structurethereof, a cyclic aliphatic hydrocarbon group containing a hetero atomin the ring structure thereof and may have a substituent (a group inwhich two hydrogen atoms have been removed from an aliphatic hydrocarbonring), a group in which the cyclic aliphatic hydrocarbon group is bondedto the terminal of the aforementioned chain-like aliphatic hydrocarbongroup, and a group in which the cyclic aliphatic group is interposedwithin the aforementioned linear or branched aliphatic hydrocarbongroup, can be given. As the linear or branched aliphatic hydrocarbongroup, the same groups as those described above can be used.

The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbonatoms, and more preferably 3 to 12 carbon atoms.

The cyclic aliphatic hydrocarbon group may be either a polycyclic groupor a monocyclic group. As the monocyclic aliphatic hydrocarbon group, agroup in which 2 hydrogen atoms have been removed from a monocycloalkaneis preferable. The monocycloalkane preferably has 3 to 6 carbon atoms,and specific examples thereof include cyclopentane and cyclohexane. Asthe polycyclic group, a group in which 2 hydrogen atoms have beenremoved from a polycycloalkane is preferable, and the polycyclic grouppreferably has 7 to 12 carbon atoms. Examples of the polycycloalkaneinclude adamantane, norbornane, isobornane, tricyclodecane andtetracyclododecane.

The cyclic aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include an alkyl group, analkoxy group, a halogen atom, a halogenated alkyl group, a hydroxylgroup and a carbonyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, ethoxy group,n-propoxy group, iso-propoxy group, n-butoxy group or tert-butoxy group,and most preferably a methoxy group or an ethoxy group.

Examples of the halogen atom for the substituent include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is preferable.

Examples of the halogenated alkyl group for the substituent includegroups in which part or all of the hydrogen atoms within theaforementioned alkyl groups has been substituted with the aforementionedhalogen atoms.

The cyclic aliphatic hydrocarbon group may have part of the carbon atomsconstituting the ring structure thereof substituted with a substituentcontaining a hetero atom. As the substituent containing a hetero atom,—O—, —C(═O)—O—, —S—, —S(═O)₂— or —S(═O)₂—O— is preferable.

Aromatic Hydrocarbon Group for Ya^(x1)

The aromatic hydrocarbon group is a hydrocarbon group having at leastone aromatic ring.

The aromatic ring is not particularly limited, as long as it is a cyclicconjugated compound having (4n+2)π electrons, and may be eithermonocyclic or polycyclic. The aromatic ring preferably has 5 to 30carbon atoms, more preferably 5 to 20 carbon atoms, and still morepreferably 6 to 15 carbon atoms, and most preferably 6 to 12 carbonatoms. Here, the number of carbon atoms within a substituent(s) is notincluded in the number of carbon atoms of the aromatic hydrocarbongroup. Examples of the aromatic ring include aromatic hydrocarbon rings,such as benzene, naphthalene, anthracene and phenanthrene; and aromatichetero rings in which part of the carbon atoms constituting theaforementioned aromatic hydrocarbon rings has been substituted with ahetero atom. Examples of the hetero atom within the aromatic heterorings include an oxygen atom, a sulfur atom and a nitrogen atom.Specific examples of the aromatic hetero ring include a pyridine ringand a thiophene ring.

Specific examples of the aromatic hydrocarbon group include a group inwhich two hydrogen atoms have been removed from the aforementionedaromatic hydrocarbon ring or aromatic hetero ring (arylene group orheteroarylene group); a group in which two hydrogen atoms have beenremoved from an aromatic compound having two or more aromatic rings(biphenyl, fluorene or the like); and a group in which one hydrogen atomof the aforementioned aromatic hydrocarbon ring or aromatic hetero ringhas been substituted with an alkylene group (a group in which onehydrogen atom has been removed from the aryl group within theaforementioned arylalkyl group such as a benzyl group, a phenethylgroup, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a1-naphthylethyl group, or a 2-naphthylethyl group, or a heteroarylalkylgroup). The alkylene group which is bonded to the aforementioned arylgroup or heteroaryl group preferably has 1 to 4 carbon atoms, morepreferably 1 or 2 carbon atoms, and most preferably 1 carbon atom.

With respect to the aromatic hydrocarbon group, the hydrogen atom withinthe aromatic hydrocarbon group may be substituted with a substituent.For example, the hydrogen atom bonded to the aromatic ring within thearomatic hydrocarbon group may be substituted with a substituent.Examples of substituents include an alkyl group, an alkoxy group, ahalogen atom, a halogenated alkyl group, and a hydroxyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

As the alkoxy group, the halogen atom and the halogenated alkyl groupfor the substituent, the same groups as the aforementioned substituentgroups for substituting a hydrogen atom within the cyclic aliphatichydrocarbon group can be used.

Divalent Linking Group Containing a Hetero Atom

In the case where Ya^(x1) represents a divalent linking group containinga hetero atom, preferable examples of the linking group include —O—,—C(═O)—O—, —C(═O)—, —O—C(═O)—O—, —C(═O)—NH—, —NH—, −NH—C(═NH)— (may besubstituted with a substituent such as an alkyl group, an acyl group orthe like), —S—, —S(═O)₂—, —S(═O)₂—O—, and a group represented by generalformula: —Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—,—C(═O)—O—Y²¹—[Y²¹—C(═O)—O]_(m″)—Y²²—, —Y²¹—O—C(═O)—Y²²— or—Y²¹—S(═O)₂—O—Y²²— [in the formulae, Y²¹ and Y²² each independentlyrepresents a divalent hydrocarbon group which may have a substituent, 0represents an oxygen atom, and m′ represents an integer of 0 to 3].

In the case where the divalent linking group containing a hetero atom is—C(═O)—NH—, —C(═O)—NH—C(═O)—, —NH— or −NH—C(═NH)—, H may be substitutedwith a substituent such as an alkyl group, an acyl group or the like.The substituent (an alkyl group, an acyl group or the like) preferablyhas 1 to 10 carbon atoms, more preferably 1 to 8, and most preferably 1to 5.

In general formulae —Y²¹—Y²²—Y²¹—, —Y²¹—C(═O)—O—,—C(═O)—O—Y²¹—[Y²¹—C(═O)—O]_(m″)—Y²²—, —Y²¹—C(═O)—Y²²— or—Y²¹—S(═O)₂—O—Y²²—, Y²¹ and Y²² each independently represents a divalenthydrocarbon group which may have a substituent. Examples of the divalenthydrocarbon group include the same groups as those described above asthe “divalent hydrocarbon group which may have a substituent” in theexplanation of the aforementioned divalent linking group.

As Y²¹, a linear aliphatic hydrocarbon group is preferable, morepreferably a linear alkylene group, still more preferably a linearalkylene group of 1 to 5 carbon atoms, and a methylene group or anethylene group is particularly desirable.

As Y²², a linear or branched aliphatic hydrocarbon group is preferable,and a methylene group, an ethylene group or an alkylmethylene group ismore preferable. The alkyl group within the alkylmethylene group ispreferably a linear alkyl group of 1 to 5 carbon atoms, more preferablya linear alkyl group of 1 to 3 carbon atoms, and most preferably amethyl group.

In the group represented by the formula —[Y²¹—C(═O)—O]_(m)″—Y²²—, m″represents an integer of 0 to 3, preferably an integer of 0 to 2, morepreferably 0 or 1, and most preferably 1. Namely, it is particularlydesirable that the group represented by the formula—[Y²¹—C(═O)—O]_(m)″—Y²²— is a group represented by the formula—Y²¹—C(═O)—O—Y²²—. Among these, a group represented by the formula—(CH₂)_(a′)—C(═O)—O—(CH₂)_(b′)— is preferable. In the formula, a′ is aninteger of 1 to 10, preferably an integer of 1 to 8, more preferably aninteger of 1 to 5, still more preferably 1 or 2, and most preferably 1.b′ is an integer of 1 to 10, preferably an integer of 1 to 8, morepreferably an integer of 1 to 5, still more preferably 1 or 2, and mostpreferably 1.

Ya^(x1) preferably represents an ester bond [—C(═O)—O—], an ether bond(—O—), —C(═O)—NH—, a linear or branched alkylene group, a combination ofthese, or a single bond, and more preferably a single bond.

In formula (a10-1), Wa^(x1) represents an aromatic hydrocarbon grouphaving a valency of (n_(ax1)+1).

Examples of the aromatic hydrocarbon group for Wa^(x1) include a groupobtained by removing (n_(ax1)+1) hydrogen atoms from an aromatic ring.The aromatic ring is not particularly limited, as long as it is a cyclicconjugated compound having (4n+2)π electrons, and may be eithermonocyclic or polycyclic. The aromatic ring preferably has 5 to 30carbon atoms, more preferably 5 to 20 carbon atoms, and still morepreferably 6 to 15 carbon atoms, and most preferably 6 to 12 carbonatoms. Examples of the aromatic ring include aromatic hydrocarbon rings,such as benzene, naphthalene, anthracene and phenanthrene; and aromatichetero rings in which part of the carbon atoms constituting theaforementioned aromatic hydrocarbon rings has been substituted with ahetero atom. Examples of the hetero atom within the aromatic heterorings include an oxygen atom, a sulfur atom and a nitrogen atom.Specific examples of the aromatic hetero ring include a pyridine ringand a thiophene ring.

In formula (a10-1), n_(ax1) is an integer of 1 to 3, preferably 1 or 2,and more preferably 1.

Specific examples of the structural unit represented by general formula(a10-1) are shown below.

In the following formulae, R^(α) represents a hydrogen atom, a methylgroup or a trifluoromethyl group.

As the structural unit (a10) contained in the component (A1), 1 kind ofstructural unit may be used, or 2 or more kinds may be used.

In the component (A1), the amount of the structural unit (a10) based onthe combined total (100 mol %) of all structural units constituting thecomponent (A1) is, for example, 0 to 80 mol %, preferably 10 to 80 mol%, more preferably 20 to 70 mol %, and still more preferably 30 to 60mol %.

When the amount of the structural unit (a10) is at least as large as thelower limit of the above-mentioned preferable range, various lithographyproperties such as sensitivity, resolution and roughness may beimproved. On the other hand, when the amount of the structural unit(a10) is no more than the upper limit of the above-mentioned range, agood balance may be achieved with the other structural units, and thelithography properties may be improved.

<<Structural Unit (a2)>>

The component (A1) preferably has, in addition to the structural unit(a1), a structural unit (a2) containing a lactone-containing cyclicgroup, an —SO₂— containing cyclic group or a carbonate-containing cyclicgroup (provided that structural units which fall under the definition ofthe structural unit (a1) are excluded).

When the component (A1) is used for forming a resist film, thelactone-containing cyclic group, the —SO₂— containing cyclic group orthe carbonate-containing cyclic group within the structural unit (a2) iseffective in improving the adhesion between the resist film and thesubstrate. In addition, by virtue of containing the structural unit(a2), for example, the acid diffusion length is appropriately adjusted,the adhesion of the resist film to the substrate is enhanced, or thesolubility during development is appropriately adjusted. As a result,the lithography properties may be enhanced.

The term “lactone-containing cyclic group” refers to a cyclic groupincluding a ring containing a —O—C(═O)— structure (lactone ring). Theterm “lactone ring” refers to a single ring containing a —O—C(O)—structure, and this ring is counted as the first ring. Alactone-containing cyclic group in which the only ring structure is thelactone ring is referred to as a monocyclic group, and groups containingother ring structures are described as polycyclic groups regardless ofthe structure of the other rings. The lactone-containing cyclic groupmay be either a monocyclic group or a polycyclic group.

The lactone-containing cyclic group for the structural unit (a2) is notparticularly limited, and an arbitrary structural unit may be used.Specific examples include groups represented by general formulae(a2-r-1) to (a2-r-7) shown below.

In the formulae, each Ra′²¹ independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom, an alkyl group, alactone-containing cyclic group, a carbonate-containing cyclic group oran —SO₂— containing cyclic group; A″ represents an oxygen atom (—O—), asulfur atom (—S—) or an alkylene group of 1 to 5 carbon atoms which maycontain an oxygen atom or a sulfur atom; n′ represents an integer of 0to 2; and m′ represents 0 or 1.

In formulae (a2-r-1) to (a2-r-7), the alkyl group for Ra′²¹ ispreferably an alkyl group of 1 to 6 carbon atoms. Further, the alkylgroup is preferably a linear alkyl group or a branched alkyl group.Specific examples include a methyl group, an ethyl group, a propylgroup, an isopropyl group, an n-butyl group, an isobutyl group, atert-butyl group, a pentyl group, an isopentyl group, a neopentyl groupand a hexyl group. Among these, a methyl group or ethyl group ispreferable, and a methyl group is particularly desirable.

The alkoxy group for Ra′²¹ is preferably an alkoxy group of 1 to 6carbon atoms.

Further, the alkoxy group is preferably a linear or branched alkoxygroup. Specific examples of the alkoxy groups include the aforementionedalkyl groups for Ra′²¹ having an oxygen atom (—O—) bonded thereto.

As examples of the halogen atom for Ra′²¹, a fluorine atom, chlorineatom, bromine atom and iodine atom can be given. Among these, a fluorineatom is preferable.

Examples of the halogenated alkyl group for Ra′²¹ include groups inwhich part or all of the hydrogen atoms within the aforementioned alkylgroup for Ra′²¹ has been substituted with the aforementioned halogenatoms. As the halogenated alkyl group, a fluorinated alkyl group ispreferable, and a perfluoroalkyl group is particularly desirable.

With respect to —COOR″ and —OC(═O)R″ for Ra′²¹, R″ represents a hydrogenatom, an alkyl group, a lactone-containing cyclic group, acarbonate-containing cyclic group or an —SO₂— containing cyclic group.

The alkyl group for R″ may be linear, branched or cyclic, and preferablyhas 1 to 15 carbon atoms.

When R″ represents a linear or branched alkyl group, it is preferably analkyl group of 1 to 10 carbon atoms, more preferably an alkyl group of 1to 5 carbon atoms, and most preferably a methyl group or an ethyl group.

When R″ is a cyclic alkyl group (cycloalkyl group), it preferably has 3to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and mostpreferably 5 to 10 carbon atoms. Specific examples include groups inwhich one or more hydrogen atoms have been removed from amonocycloalkane or a polycycloalkane such as a bicycloalkane,tricycloalkane or tetracycloalkane which may or may not be substitutedwith a fluorine atom or a fluorinated alkyl group. Specific examplesinclude groups in which one or more hydrogen atoms have been removedfrom a monocycloalkane such as cyclopentane or cyclohexane; and groupsin which one or more hydrogen atoms have been removed from apolycycloalkane such as adamantane, norbornane, isobornane,tricyclodecane or tetracyclododecane.

Examples of the lactone-containing cyclic group for R″ include groupsrepresented by the aforementioned general formulae (a2-r-1) to (a2-r-7).The carbonate-containing cyclic group for R″ is the same as defined forthe carbonate-containing cyclic group described later. Specific examplesof the carbonate-containing cyclic group include groups represented bygeneral formulae (ax3-r-1) to (ax3-r-3).

The —SO₂— containing cyclic group for R″ is the same as defined for the—SO₂— containing cyclic group described later. Specific examples of the—SO₂— containing cyclic group include groups represented by generalformulae (a5-r-1) to (a5-r-4).

The hydroxyalkyl group for Ra′²¹ preferably has 1 to 6 carbon atoms, andspecific examples thereof include the alkyl groups for Ra′²¹ in which atleast one hydrogen atom has been substituted with a hydroxy group.

In formulae (a2-r-2), (a2-r-3) and (a2-r-5), as the alkylene group of 1to 5 carbon atoms represented by A″, a linear or branched alkylene groupis preferable, and examples thereof include a methylene group, anethylene group, an n-propylene group and an isopropylene group. Examplesof alkylene groups that contain an oxygen atom or a sulfur atom includethe aforementioned alkylene groups in which —O— or —S— is bonded to theterminal of the alkylene group or present between the carbon atoms ofthe alkylene group. Specific examples of such alkylene groups include—O—CH₂—, —CH₂—O—CH₂—, —S—CH₂— and —CH₂—S—CH₂—. As A″, an alkylene groupof 1 to 5 carbon atoms or —O— is preferable, more preferably an alkylenegroup of 1 to 5 carbon atoms, and most preferably a methylene group.

Specific examples of the groups represented by the aforementionedgeneral formulae (a2-r-1) to (a2-r-7) are shown below.

An “—SO₂— containing cyclic group” refers to a cyclic group having aring containing —SO₂— within the ring structure thereof, i.e., a cyclicgroup in which the sulfur atom (S) within —SO₂— forms part of the ringskeleton of the cyclic group. The ring containing —SO₂— within the ringskeleton thereof is counted as the first ring. A cyclic group in whichthe only ring structure is the ring that contains —SO₂— in the ringskeleton thereof is referred to as a monocyclic group, and a groupcontaining other ring structures is described as a polycyclic groupregardless of the structure of the other rings. The —SO₂— containingcyclic group may be either a monocyclic group or a polycyclic group.

As the —SO₂— containing cyclic group, a cyclic group containing —O—SO₂—within the ring skeleton thereof, i.e., a cyclic group containing asultone ring in which —O—S— within the —O—SO₂— group forms part of thering skeleton thereof is particularly desirable.

More specific examples of the —SO₂— containing cyclic group includegroups represented by general formulas (a5-r-1) to (a5-r-4) shown below.

In the formulae, each Ra′⁵¹ independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom, an alkyl group, alactone-containing cyclic group, a carbonate-containing cyclic group oran —SO₂— containing cyclic group; A″ represents an oxygen atom, a sulfuratom or an alkylene group of 1 to 5 carbon atoms which may contain anoxygen atom or a sulfur atom; and n′ represents an integer of 0 to 2.

In general formulae (a5-r-1) and (a5-r-2), A″ is the same as defined forA″ in general formulae (a2-r-2), (a2-r-3) and (a2-r-5).

Examples of the alkyl group, alkoxy group, halogen atom, halogenatedalkyl group, —COOR″, —OC(═O)R″ and hydroxyalkyl group for Ra′^(S1)include the same groups as those described above in the explanation ofRa′²¹ in the general formulas (a2-r-1) to (a2-r-7).

Specific examples of the groups represented by the aforementionedgeneral formulae (a5-r-1) to (a5-r-4) are shown below. In the formulaeshown below, “Ac” represents an acetyl group.

The term “carbonate-containing cyclic group” refers to a cyclic groupincluding a ring containing a —O—C(═O)—O— structure (carbonate ring).The term “carbonate ring” refers to a single ring containing a—O—C(═O)—O— structure, and this ring is counted as the first ring. Acarbonate-containing cyclic group in which the only ring structure isthe carbonate ring is referred to as a monocyclic group, and groupscontaining other ring structures are described as polycyclic groupsregardless of the structure of the other rings. The carbonate-containingcyclic group may be either a monocyclic group or a polycyclic group.

The carbonate-containing cyclic group is not particularly limited, andan arbitrary group may be used. Specific examples include groupsrepresented by general formulae (ax3-r-1) to (ax3-r-3) shown below.

In the formulae, each Ra′^(x31) independently represents a hydrogenatom, an alkyl group, an alkoxy group, a halogen atom, a halogenatedalkyl group, a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group ora cyano group; R″ represents a hydrogen atom, an alkyl group, alactone-containing cyclic group, a carbonate-containing cyclic group oran —SO₂— containing cyclic group; A″ represents an oxygen atom, a sulfuratom or an alkylene group of 1 to 5 carbon atoms which may contain anoxygen atom or a sulfur atom; p′ represents an integer of 0 to 3; and q′represents 0 or 1.

In general formulae (ax3-r-2) and (ax3-r-3), A″ is the same as definedfor A″ in general formulae (a2-r-2), (a2-r-3) and (a2-r-5).

Examples of the alkyl group, alkoxy group, halogen atom, halogenatedalkyl group, —COOR″, —OC(═O)R″ and hydroxyalkyl group for Ra′³¹ includethe same groups as those described above in the explanation of Ra′²¹ inthe general formulas (a2-r-1) to (a2-r-7).

Specific examples of the groups represented by the aforementionedgeneral formulae (ax3-r-1) to (ax3-r-3) are shown below.

As the structural unit (a2), a structural unit derived from an acrylateester which may have the hydrogen atom bonded to the carbon atom on theα-position substituted with a substituent is preferable.

The structural unit (a2) is preferably a structural unit represented bygeneral formula (a2-1) shown below.

In the formula, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms; Ya²¹represents a single bond or a divalent linking group; La²¹ represents—O—, —COO—, —CON(R′)—, —OCO—, —CONHCO— or —CONHCS—; and R′ represents ahydrogen atom or a methyl group; provided that, when La²¹ represents—O—, Ya²¹ does not represents —CO—; and Ra²¹ represents alactone-containing cyclic group, a carbonate-containing cyclic group oran —SO₂— containing cyclic group.

In the formula (a2-1), R is the same as defined above. As R, a hydrogenatom, an alkyl group of 1 to 5 carbon atoms or a fluorinated alkyl groupof 1 to 5 carbon atoms is preferable, and a hydrogen atom or a methylgroup is particularly desirable in terms of industrial availability.

In the formula (a2-1), the divalent linking group for Ya²¹ is notparticularly limited, and preferable examples thereof include a divalenthydrocarbon group which may have a substituent and a divalent linkinggroup containing a hetero atom. The divalent hydrocarbon group which mayhave a substituent and the divalent linking group containing a heteroatom for Ya²¹ are the same as defined for the divalent hydrocarbon groupwhich may have a substituent and the divalent linking group containing ahetero atom described above in relation to Ya^(x) in general formula(a10-1).

Ya²¹ preferably represents an ester bond [—C(═O)—O—], an ether bond(—O—), a linear or branched alkylene group, a combination of these, or asingle bond.

In the formula (a2-1), Ra²¹ represents a lactone-containing cyclicgroup, an —SO₂— containing cyclic group or a carbonate-containing cyclicgroup.

Preferable examples of the lactone-containing cyclic group, the —SO₂—containing cyclic group and the carbonate-containing cyclic group forRa²¹ include groups represented by general formulae (a2-r-1) to(a2-r-7), groups represented by general formulae (a5-r-1) to (a5-r-4)and groups represented by general formulae (ax3-r-1) to (ax3-r-3).

Among the above examples, a lactone-containing cyclic group or a —SO₂—containing cyclic group is preferable, and a group represented bygeneral formula (a2-r-1), (a2-r-2), (a2-r-6) or (a5-r-1) is morepreferable. Specifically, a group represented by any of chemicalformulae (r-1c-1-1) to (r-1c-1-7), (r-1c-2-1) to (r-1c-2-18),(r-1c-6-1), (r-s1-1-1) and (r-s1-1-18) is still more preferable.

As the structural unit (a2) contained in the component (A1), 1 kind ofstructural unit may be used, or 2 or more kinds may be used.

When the component (A1) contains the structural unit (a2), the amount ofthe structural unit (a2) based on the combined total (100 mol %) of allstructural units constituting the component (A1) is preferably 1 to 50mol %, more preferably 5 to 45 mol %, still more preferably 10 to 40 mol%, and most preferably 10 to 30 mol %.

When the amount of the structural unit (a2) is at least as large as thelower limit of the above preferable range, the effect of using thestructural unit (a2) can be satisfactorily achieved. On the other hand,when the amount of the structural unit (a2) is no more than the upperlimit of the above preferable range, a good balance can be achieved withthe other structural units, and various lithography properties andpattern shape can be improved.

<<Structural Unit (a3)>>

The component (A1) may have, in addition to the structural unit (a1), astructural unit (a3) containing a polar group-containing aliphatichydrocarbon group (provided that the structural units that fall underthe definition of structural units (a1) and (a2) are excluded). When thecomponent (A1) includes the structural unit (a3), the hydrophilicity ofthe component (A1) is enhanced, thereby contributing to improvement inresolution.

Examples of the polar group include a hydroxyl group, cyano group,carboxyl group, or hydroxyalkyl group in which part of the hydrogenatoms of the alkyl group have been substituted with fluorine atoms,although a hydroxyl group is particularly desirable.

Examples of the aliphatic hydrocarbon group include linear or branchedhydrocarbon groups (preferably alkylene groups) of 1 to 10 carbon atoms,and cyclic aliphatic hydrocarbon groups (cyclic groups). These cyclicgroups can be selected appropriately from the multitude of groups thathave been proposed for the resins of resist compositions designed foruse with ArF excimer lasers. The cyclic group is preferably a polycyclicgroup, more preferably a polycyclic group of 7 to 30 carbon atoms.

Of the various possibilities, structural units derived from an acrylateester that include an aliphatic polycyclic group that contains ahydroxyl group, cyano group, carboxyl group or a hydroxyalkyl group inwhich part of the hydrogen atoms of the alkyl group have beensubstituted with fluorine atoms are particularly desirable. Examples ofthe polycyclic group include groups in which two or more hydrogen atomshave been removed from a bicycloalkane, tricycloalkane, tetracycloalkaneor the like. Specific examples include groups in which two or morehydrogen atoms have been removed from a polycycloalkane such asadamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane. Of these polycyclic groups, groups in which two ormore hydrogen atoms have been removed from adamantane, norbornane ortetracyclododecane are preferred industrially.

As the structural unit (a3), there is no particular limitation as longas it is a structural unit containing a polar group-containing aliphatichydrocarbon group, and an arbitrary structural unit may be used.

The structural unit (a3) is preferably a structural unit derived from anacrylate ester which may have the hydrogen atom bonded to the carbonatom on the α-position substituted with a substituent and contains apolar group-containing aliphatic hydrocarbon group.

When the aliphatic hydrocarbon group within the polar group-containingaliphatic hydrocarbon group is a linear or branched hydrocarbon group of1 to 10 carbon atoms, the structural unit (a3) is preferably astructural unit derived from a hydroxyethyl ester of acrylic acid.

On the other hand, in the structural unit (a3), when the hydrocarbongroup within the polar group-containing aliphatic hydrocarbon group is apolycyclic group, structural units represented by formulas (a3-1),(a3-2), and (a3-3) shown below are preferable.

In the formulas, R is the same as defined above; j is an integer of 1 to3; k is an integer of 1 to 3; t′ is an integer of 1 to 3; 1 is aninteger of 1 to 5; and s is an integer of 1 to 3.

In formula (a3-1), j is preferably 1 or 2, and more preferably 1. When jis 2, it is preferable that the hydroxyl groups be bonded to the 3rd and5th positions of the adamantyl group. When j is 1, it is preferable thatthe hydroxyl group be bonded to the 3rd position of the adamantyl group.

j is preferably 1, and it is particularly desirable that the hydroxylgroup be bonded to the 3rd position of the adamantyl group.

In formula (a3-2), k is preferably 1. The cyano group is preferablybonded to the 5th or 6th position of the norbornyl group.

In formula (a3-3), t′ is preferably 1. 1 is preferably 1. s ispreferably 1. Further, it is preferable that a 2-norbornyl group or3-norbornyl group be bonded to the terminal of the carboxy group of theacrylic acid. The fluorinated alkyl alcohol is preferably bonded to the5th or 6th position of the norbornyl group.

As the structural unit (a3) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

When the component (A1) contains the structural unit (a3), the amount ofthe structural unit (a3) within the component (A1) based on the combinedtotal of all structural units constituting the component (A1) ispreferably 1 to 40 mol %, more preferably 2 to 30 mol %, still morepreferably 5 to 25 mol %, and still more preferably 5 to 20 mol %.

When the amount of the structural unit (a3) is at least as large as thelower limit of the above preferable range, the effect of using thestructural unit (a3) may be satisfactorily achieved. On the other hand,when the amount of the structural unit (a3) is no more than the upperlimit of the above preferable range, a good balance may be achieved withthe other structural units, and various lithography properties may beimproved.

<<Other Structural Units>>

The component (A1) may be further include a structural unit other thanthe structural units (a10), (a1), (a2) and (a3).

Examples of other structural units include a structural unit derivedfrom styrene, a structural unit derived from a styrene derivative(provided that the structural units that fall under the definition ofstructural unit (a10) are excluded), and a structural unit containing anacid non-dissociable, aliphatic cyclic group.

In the resist composition, as the component (A1), one kind of compoundmay be used, or two or more kinds of compounds may be used incombination.

The component (A1) preferably includes a polymeric compound (A1-1)having a structural unit (a1) (hereafter, sometimes referred to as“component (A1-1)”).

Preferable examples of the component (A1-1) include a polymeric compoundhaving a repeating structure of the structural units (a1) and (a2); anda polymeric compound having a repeating structure of the structuralunits (a1) and (a10).

In addition to the combination of the two structural units describedabove, the structural unit described above may be combined appropriatelyin order to obtain desired effects as a third structural unit, oralternatively, three or more of such structural units may be combined.The third structural unit is preferably the structural unit (a3).

The component (A1) can be produced, for example, by dissolving themonomers corresponding with each of the structural units in apolymerization solvent, followed by addition of a radical polymerizationinitiator such as azobisisobutyronitrile (AIBN) ordimethyl-2,2′-azobisisoutyrate (e.g., V-601). Alternatively, thecomponent (A1) can be prepared by dissolving a monomer from which thestructural unit (a1) is derived, and a precursor monomer (monomer forwhich the functional group is protected) from which the structural unitother than the structural unit (a1) is derived in a polymerizationsolvent, polymerizing the dissolved monomers using the radicalpolymerization initiator described above, followed by performing adeprotection reaction. In the polymerization, a chain transfer agentsuch as HS—CH₂—CH₂—CH₂—C(CF₃)₂—OH may be used to introduce a —C(CF₃)₂—OHgroup at the terminal(s) of the polymer. Such a copolymer havingintroduced a hydroxyalkyl group in which some of the hydrogen atoms ofthe alkyl group are substituted with fluorine atoms is effective inreducing developing defects and LER (line edge roughness: unevenness ofthe side walls of a line pattern).

The weight average molecular weight (Mw) (the polystyrene equivalentvalue determined by gel permeation chromatography (GPC)) of thecomponent (A1) is not particularly limited, but is preferably 1,000 to50,000, more preferably 2,000 to 30,000, and still more preferably 3,000to 20,000.

When the Mw of the component (A1) is no more than the upper limit of theabove-mentioned preferable range, the resist composition exhibits asatisfactory solubility in a resist solvent. On the other hand, when theMw of the component (A1) is at least as large as the lower limit of theabove-mentioned preferable range, dry etching resistance and thecross-sectional shape of the resist pattern becomes satisfactory.

The dispersity (Mw/Mn) of the component (A1) is not particularlylimited, but is preferably 1.0 to 4.0, more preferably 1.0 to 3.0, andmost preferably 1.1 to 2.0. Here, Mn is the number average molecularweight.

Component (A2)

In the resist composition of the present embodiment, as the component(A), “a base component which exhibits changed solubility in a developingsolution under action of acid” other than the component (A1) (hereafter,referred to as “component (A2)”) may be used in combination.

As the component (A2), there is no particular limitation, and any of themultitude of conventional base resins used within chemically amplifiedresist compositions may be arbitrarily selected for use.

As the component (A2), one kind of a polymer or a low molecular weightcompound may be used, or a combination of two or more kinds may be used.

In the component (A), the amount of the component (A1) based on thetotal weight of the component (A) is preferably 25% by weight or more,more preferably 50% by weight or more, still more preferably 75% byweight or more, and may be even 100% by weight. When the amount of thecomponent (A1) is 25% by weight or more, a resist pattern with improvedlithography properties such as improvement in roughness may be reliablyformed. Such effects are significant in lithography using electron beamor EUV.

In the resist composition of the present embodiment, the amount of thecomponent (A) may be appropriately adjusted depending on the thicknessof the resist film to be formed, and the like.

<Component (B)>

The component (B) is an acid generator component which generates acidupon exposure. In the resist composition of the present embodiment, thecomponent (B) includes an acid generator (B1) containing a compoundrepresented by general formula (b1) (hereafter, also is referred to as“component (B1)”).

<<Component (B1)>>

The component (B1) is an acid generator containing a compoundrepresented by general formula (b1) shown below.

In the formula, R^(b1) represents an aryl group which may have asubstituent; R^(b2) and R^(b3) each independently represents an arylgroup which may have a substituent or an alkyl group which may have asubstituent;

R^(b2) and R^(b3) may be mutually bonded to form a ring with the sulfuratom;

provided that at least one of the aryl group represented by R^(b1) andthe aryl group or the alkyl group represented by R^(b2) or R^(b3) has asubstituent containing a halogen atom, and at least one of the arylgroup represented by R^(b1) and the aryl group or the alkyl grouprepresented by R^(b2) or R^(b3) has a substituent containing a sulfonylgroup; and X⁻ represents a counteranion.

In formula (b1), examples of the aryl group represented by R^(b1)include a group in which one hydrogen atom has been removed from anaromatic hydrocarbon ring such as benzene, naphthalene, anthracene,phenanthrene, biphenyl or fluorene. Among these examples, as the arylgroup represented by R^(b1), a group in which one hydrogen atom has beenremoved from benzene or naphthalene (a phenyl group or a naphthyl group)is preferable, and a group in which one hydrogen atom has been removedfrom benzene (a phenyl group) is more preferable.

In the formula, the aryl group represented by R^(b2) or R^(b3) is thesame as defined for the aryl group represented by R^(b1).

Among these examples, as the aryl group represented by R^(b2) or R^(b3),a group in which one hydrogen atom has been removed from benzene ornaphthalene (a phenyl group or a naphthyl group) is preferable, and agroup in which one hydrogen atom has been removed from benzene (a phenylgroup) is more preferable.

In formula (b1), the alkyl group represented by R^(b2) or R^(b3) may bechain or cyclic.

Chain alkyl group which may have a substituent:

The chain alkyl group represented by R^(b2) or R^(b3) may be linear orbranched.

The linear alkyl group preferably has 1 to 20 carbon atoms, morepreferably 1 to 15 carbon atoms, and still more preferably 1 to 10carbon atoms. Specific examples include a methyl group, an ethyl group,a propyl group, a butyl group, a pentyl group, a hexyl group, a heptylgroup, an octyl group, a nonyl group, a decyl group, an undecyl group, adodecyl group, a tridecyl group, an isotridecyl group, a tetradecylgroup, a pentadecyl group, a hexadecyl group, an isohexadecyl group, aheptadecyl group, an octadecyl group, a nonadecyl group, an icosylgroup, a henicosyl group and a docosyl group.

The branched alkyl group preferably has 3 to 20 carbon atoms, morepreferably 3 to 15 carbon atoms, and still more preferably 3 to 10carbon atoms. Specific examples include a 1-methylethyl group, a1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a3-methylpentyl group and a 4-methylpentyl group.

Cyclic alkyl group which may have a substituent:

The cyclic alkyl group represented by R^(b2) or R^(b3) preferably has 3to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and still morepreferably 5 to 10 carbon atoms. Examples thereof include groups inwhich one or more of the hydrogen atoms have been removed from amonocycloalkane; and groups in which one or more of the hydrogen atomshave been removed from a polycycloalkane such as a bicycloalkane, atricycloalkane, or a tetracycloalkane. The monocycloalkane preferablyhas 3 to 6 carbon atoms, and specific examples thereof includecyclopentane and cyclohexane. Examples of polycycloalkanes includeadamantane, norbornane, isobornane, tricyclodecane andtetracyclododecane.

Examples of the substituent for the aryl group represented by any ofR^(b1) to R^(b3) or the alkyl group represented by R^(b2) or R^(b3)include an alkyl group, an alkoxy group, a halogen atom, a halogenatedalkyl group, a sulfonyl group, a hydroxy group, a carbonyl group, acyano group and an amino group, an aryl group having 6 to 20 carbonatoms, and a group represented by any one of formulae (ca-r-1) to(ca-r-7) shown below.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, ethoxy group,n-propoxy group, iso-propoxy group, n-butoxy group or tert-butoxy group,and most preferably a methoxy group or an ethoxy group.

Examples of the halogen atom for the substituent include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is preferable.

Example of the aforementioned halogenated alkyl group includes a groupin which a part or all of the hydrogen atoms within an alkyl group of 1to 5 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group,an n-butyl group or a tert-butyl group) have been substituted with theaforementioned halogen atoms.

In the formulae, each R′²⁰¹ independently represents a hydrogen atom, acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent, or a chain-like alkenyl group which mayhave a substituent.

The cyclic group (which may have a substituent) represented by R′²⁰¹ isthe same as defined for the aryl group (which may have a substituent)represented by R^(b1) in the aforementioned formula (b1) and the cyclicalkyl group represented by R^(b2) or R^(b3) in the aforementionedformula (b1).

The chain alkyl group (which may have a substituent) represented byR′²⁰¹ is the same as defined for the chain alkyl group (which may have asubstituent) represented by R^(b2) or R^(b3) in the aforementionedformula (b1).

Alternatively, the cyclic group (which may have a substituent) or thechain alkyl group (which may have a substituent) represented by R′²⁰¹may be the same as defined for the acid dissociable group represented bythe aforementioned formula (a1-r-2).

The chain alkenyl group (which may have a substituent) for R′²⁰¹ may belinear or branched, and preferably has 2 to 10 carbon atoms, morepreferably 2 to 5 carbon atoms, still more preferably 2 to 4 carbonatoms, and most preferably 3 carbon atoms. Examples of linear alkenylgroups include a vinyl group, a propenyl group (an allyl group) and abutynyl group. Examples of branched alkenyl groups include a1-methylvinyl group, a 2-methylvinyl group, a 1-methylpropenyl group anda 2-methylpropenyl group.

Among these examples, as the chain-like alkenyl group, a linear alkenylgroup is preferable, a vinyl group or a propenyl group is morepreferable, and a vinyl group is most preferable.

In formula (b1), in the case where R^(b2) and R^(b3) mutually bonded toform a ring with the sulfur atom, R^(b2) and R^(b3) may be bondedthrough a hetero atom such as a sulfur atom, an oxygen atom or anitrogen atom, or a functional group such as a carbonyl group, —SO—,—COO—, —CONH— or —N(R_(N))— (R_(N) represents an alkyl group having 1 to5 carbon atoms). The ring containing the sulfur atom in the skeletonthereof is preferably a 3 to 10-membered ring, and most preferably a 5to 7-membered ring. Specific examples of the ring formed include athiophene ring, a thiazole ring, a benzothiophene ring, a thianthrenering, a benzothiophene ring, a dibenzothiophene ring, a 9H-thioxanthenering, a thioxanthone ring, a phenoxathiin ring, a tetrahydrothiopheniumring, and a tetrahydrothiopyranium ring.

In formula (b1), at least one of R^(b1) to R^(b3) represents an arylgroup or alkyl group having a substituent containing a halogen atom, andat least one of R^(b1) to R^(b3) represents an aryl group or alkyl grouphaving a substituent containing a sulfonyl group.

Regarding R^(b1) to R^(b3), examples of the substituent containing ahalogen atom include a halogen atom and a halogenated alkyl group.Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom, and a fluorine atom is preferable.Examples of the halogenated alkyl group include a group in which some orall hydrogen atoms in an alkyl group having 1 to 5 carbon atoms such asa methyl group, an ethyl group, a propyl group, an n-butyl group, or atert-butyl group have been substituted with any of the above-mentionedhalogen atoms.

Regarding R^(b1) to R^(b3), examples of the substituent containing asulfonyl group include a monovalent group represented by the formula:—SO₂—R^(b4) (wherein R^(b4) represents a linear or branched alkyl groupwhich may have a substituent, an alicyclic group which may have asubstituent, or an aromatic hydrocarbon group which may have asubstituent).

Examples of the linear or branched alkyl group represented by R^(b4)include a methyl group, an ethyl group, a propyl group, an isopropylgroup, an n-butyl group, an isobutyl group, a tert-butyl group, a pentylgroup, an isopentyl group and a neopentyl group, preferably a methylgroup or an ethyl group, and more preferably a methyl group.

As the substituent for the linear or branched alkyl group represented byR^(b4), a halogen atom, a halogenated alkyl group having 1 to 5 carbonatoms, an alkoxy group having 1 to 5 carbon atoms, a hydroxy group, acarbonyl group and a carboxy group may be mentioned.

The alicyclic hydrocarbon group represented by R^(b4) preferably has 3to 20 carbon atoms, more preferably 3 to 12 carbon atoms. The alicyclichydrocarbon group may be polycyclic or monocyclic. As the monocyclicalicyclic hydrocarbon group, a group in which one or more hydrogen atomshave been removed from a monocycloalkane is preferable. Themonocycloalkane preferably has 3 to 6 carbon atoms, and specificexamples thereof include cyclobutane, cyclopentane and cyclohexane. Asthe polycyclic alicyclic hydrocarbon group, a group in which one or morehydrogen atoms have been removed from a polycycloalkane is preferable,and the polycyclic group preferably has 7 to 12 carbon atoms. Examplesof the polycycloalkane include adamantane, norbornane, isobornane,tricyclodecane and tetracyclododecane.

As the substituent for the alicyclic hydrocarbon group represented byR^(b4), the same groups as those defined for Ra⁰⁵ may be mentioned.

Examples of the aromatic hydrocarbon group represented by R^(b4) includea group in which one hydrogen atom has been removed from an aromatichydrocarbon ring such as benzene, naphthalene, anthracene, phenanthrene,biphenyl or fluorene. Among these examples, as the aryl grouprepresented by R^(b1) to R^(b3), a group in which one hydrogen atom hasbeen removed from benzene or naphthalene (a phenyl group or a naphthylgroup) is preferable, and a group in which one hydrogen atom has beenremoved from benzene (a phenyl group) is more preferable.

As the substituent for the aromatic hydrocarbon group represented byR^(b4), the same groups as those defined for Ra⁰⁵ may be mentioned.

In formula (b1), in the case where R^(b2) and R^(b3) are mutually bondedto form a ring with the sulfur atom, one carbon atom of the ringskeleton may be replaced by a divalent sulfonyl group. The divalentsulfonyl group may be —SO₂—. Alternatively, the divalent sulfonyl groupmay be a sulfonyl group (—SO₂—) having a functional group other than asulfonyl group or an atom bonded thereto, such as —SO₃—, —SO₂NH—, and—SO₂N(R_(N))—. In such case, the ring formed by R^(b2) and R^(b3) bondedtogether with the sulfur atom is not particularly limited, and the ringmay or may not have an aromatic ring. In the case where the ring doesnot contain an aromatic ring, examples of the ring include a1,4-dithiane-1,1-dioxide ring skeleton. In the case where the ringcontains an aromatic ring, examples of the ring include a condensedbicyclic ring containing at least one benzene ring or a condensedtricyclic ring containing at least one benzene ring. Regarding theskeleton formed by the sulfur atom in the formula, R^(b2), R^(b3) andthe divalent sulfonyl group, examples of the condensed bicyclic ringinclude a benzo[1,3]dithiol-1,1-dioxide skeleton, and examples of thecondensed tricyclic ring include a thianthrene-5,5-dioxide skeleton.

In terms of the effects of the present embodiment, in formula (b1), atleast one of R^(b1) to R^(b3) is preferably an aryl group having asubstituent containing a halogen atom, and at least one of R^(b1) toR^(b3) is preferably an aryl group having a substituent containing asulfonyl group.

Further, in terms of the effects of the present embodiment, in formula(b1), at least one of R^(b1) to R^(b3) is preferably an aryl grouphaving a substituent containing a halogen atom at a meta-position, andat least one of R^(b1) to R^(b3) is an aryl group having a substituentcontaining a sulfonyl group at a meta-position and/or a para-position.

In the cation moiety of the component (B1), the number of thesubstituent containing a halogen atom and the number of the substituentcontaining a sulfonyl group are not particularly limited, and may beappropriately selected depending on the kind of the anion moiety of thecomponent (B1), and the kind of the component (A).

Specific examples of the cation of the compound represented by theaforementioned formula (b1) include cations represented by formulae(ca-01-1) to (ca-01-38) shown below.

In formula (b1-1), X⁻ represents a counteranion.

X⁻ is not particularly limited, and any anion known as an anion moietyof an acid-generator component for a resist composition may beappropriately selected.

Examples of X⁻ include an anion represented by general formula(b1-1-an1) shown below, an anion represented by general formula(b1-1-an2) shown below, and an anion represented by general formula(b1-1-an3) shown below.

In the formulae, R¹⁰¹ and R¹⁰⁴ to R¹⁰⁸ each independently represents acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent or a chain-like alkenyl group which mayhave a substituent, provided that R¹⁰⁴ and R¹⁰⁵ may be mutually bondedto form a ring structure; R¹⁰² represents a fluorine atom or afluorinated alkyl group having 1 to 5 carbon atoms; Y¹⁰¹ represents asingle bond or a divalent group containing an oxygen atom; V¹⁰¹ to V¹⁰³each independently represents a single bond, an alkylene group or afluorinated alkylene group; L¹⁰¹ and L¹⁰² each independently representsa single bond or an oxygen atom; and L¹⁰³ to L¹⁰⁵ each independentlyrepresents a single bond, —CO— or —SO₂—.

Anion Represented by General Formula (b1-1-an1)

In the formula (b1-1-an1), R¹⁰¹ represents a cyclic group which may havea substituent, a chain-like alkyl group which may have a substituent ora chain-like alkenyl group which may have a substituent.

Cyclic group which may have a substituent:

The cyclic group is preferably a cyclic hydrocarbon group, and thecyclic hydrocarbon group may be either an aromatic hydrocarbon group oran aliphatic hydrocarbon group. An “aliphatic hydrocarbon group” refersto a hydrocarbon group that has no aromaticity. The aliphatichydrocarbon group may be either saturated or unsaturated, but ingeneral, the aliphatic hydrocarbon group is preferably saturated.

The aromatic hydrocarbon group for R¹⁰¹ is a hydrocarbon group having anaromatic ring. The aromatic hydrocarbon group preferably has 3 to 30carbon atoms, more preferably 5 to 30 carbon atoms, still morepreferably 5 to 20 carbon atoms, and most preferably 6 to 18 carbonatoms. Here, the number of carbon atoms within a substituent(s) is notincluded in the number of carbon atoms of the aromatic hydrocarbongroup.

Examples of the aromatic ring contained in the aromatic hydrocarbongroup represented by R¹⁰¹ include benzene, fluorene, naphthalene,anthracene, phenanthrene and biphenyl; and aromatic hetero rings inwhich part of the carbon atoms constituting the aforementioned aromaticrings has been substituted with a hetero atom. Examples of the heteroatom within the aromatic hetero rings include an oxygen atom, a sulfuratom and a nitrogen atom.

Specific examples of the aromatic hydrocarbon group represented by R¹⁰¹include a group in which one hydrogen atom has been removed from anaromatic ring (an aryl group, such as a phenyl group or a naphthylgroup), a group in which one hydrogen atom of the aforementionedaromatic ring has been substituted with an alkylene group (an arylalkylgroup, such as a benzyl group, a phenethyl group, a 1-naphthylmethylgroup, a 2-naphthylmethyl group, a 1-naphthylethyl group or a2-naphthylethyl group), and a group in which one hydrogen atom has beenremoved from a condensed ring of the aforementioned aromatic ring and abridged aliphatic ring such as bicycloheptane or bicyclooctane. Thealkylene group (alkyl chain within the arylalkyl group) preferably has 1to 4 carbon atom, more preferably 1 or 2, and most preferably 1.

Examples of the cyclic aliphatic hydrocarbon group for R¹⁰¹ includealiphatic hydrocarbon groups containing a ring in the structure thereof.

As examples of the hydrocarbon group containing a ring in the structurethereof, an alicyclic hydrocarbon group (a group in which one hydrogenatom has been removed from an aliphatic hydrocarbon ring), a group inwhich the alicyclic hydrocarbon group is bonded to the terminal of theaforementioned chain-like aliphatic hydrocarbon group, and a group inwhich the alicyclic group is interposed within the aforementioned linearor branched aliphatic hydrocarbon group, can be given.

The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, andmore preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be either a polycyclic group or amonocyclic group. As the monocyclic alicyclic hydrocarbon group, a groupin which one or more hydrogen atoms have been removed from amonocycloalkane is preferable. The monocycloalkane preferably has 3 to 6carbon atoms, and specific examples thereof include cyclopentane andcyclohexane. As the polycyclic alicyclic hydrocarbon group, a group inwhich one or more hydrogen atoms have been removed from apolycycloalkane is preferable, and the polycyclic group preferably has 7to 30 carbon atoms. Among polycycloalkanes, a polycycloalkane having abridged ring polycyclic skeleton, such as adamantane, norbornane,isobornane, tricyclodecane or tetracyclodpdecane, and a polycycloalkanehaving a condensed ring polycyclic skeleton, such as a cyclic grouphaving a steroid skeleton are preferable.

Among these examples, as the cyclic aliphatic hydrocarbon group forR¹⁰¹, a group in which one or more hydrogen atoms have been removed froma monocycloalkane or a polycycloalkane is preferable, a group in whichone or more hydrogen atoms have been removed from a polycycloalkane ismore preferable, an adamantyl group or a norbornyl group is still morepreferable, and an adamantyl group is most preferable.

The linear aliphatic hydrocarbon group which may be bonded to thealicyclic hydrocarbon group preferably has 1 to 10 carbon atoms, morepreferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbonatoms, and most preferably 1 to 3 carbon atoms. As the linear aliphatichydrocarbon group, a linear alkylene group is preferable. Specificexamples thereof include a methylene group [—CH₂—], an ethylene group[—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], a tetramethylene group[—(CH₂)₄—] and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group which may be bonded to thealicyclic hydrocarbon group preferably has 2 to 10 carbon atoms, morepreferably 3 to 6 carbon atoms, still more preferably 3 or 4 carbonatoms, and most preferably 3 carbon atoms. As the branched aliphatichydrocarbon group, branched alkylene groups are preferred, and specificexamples include various alkylalkylene groups, including alkylmethylenegroups such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—,—C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—; alkylethylene groups such as—CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and—C(CH₂CH₃)₂—CH₂—; alkyltrimethylene groups such as —CH(CH₃)CH₂CH₂—, and—CH₂CH(CH₃)CH₂—; and alkyltetramethylene groups such as—CH(CH₃)CH₂CH₂CH₂—, and —CH₂CH(CH₃)CH₂CH₂—. As the alkyl group withinthe alkylalkylene group, a linear alkyl group of 1 to 5 carbon atoms ispreferable.

The cyclic hydrocarbon group for R¹⁰¹ may contain a hetero atom such asa heterocycle. Specific examples include lactone-containing cyclicgroups represented by the aforementioned general formulae (a2-r-1) to(a2-r-7), the —SO₂— containing cyclic group represented by theaforementioned formulae (a5-r-1) to (a5-r-4), and other heterocyclicgroups represented by the aforementioned chemical formulae (r-hr-1) to(r-hr-16).

As the substituent for the cyclic group for R¹⁰¹, an alkyl group, analkoxy group, a halogen atom, a halogenated alkyl group, a hydroxylgroup, a carbonyl group, a nitro group or the like can be used.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, ethoxy group,n-propoxy group, iso-propoxy group, n-butoxy group or tert-butoxy group,and most preferably a methoxy group or an ethoxy group.

Examples of the halogen atom for the substituent include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is preferable.

Example of the aforementioned halogenated alkyl group includes a groupin which a part or all of the hydrogen atoms within an alkyl group of 1to 5 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group,an n-butyl group or a tert-butyl group) have been substituted with theaforementioned halogen atoms.

The carbonyl group as the substituent is a group that substitutes amethylene group (—CH₂—) constituting the cyclic hydrocarbon group.

Chain alkyl group which may have a substituent:

The chain-like alkyl group for R¹⁰¹ may be linear or branched.

The linear alkyl group preferably has 1 to 20 carbon atoms, morepreferably 1 to 15, and most preferably 1 to 10. Specific examplesinclude a methyl group, an ethyl group, a propyl group, a butyl group, apentyl group, a hexyl group, a heptyl group, an octyl group, a nonylgroup, a decyl group, an undecyl group, a dodecyl group, a tridecylgroup, an isotridecyl group, a tetradecyl group, a pentadecyl group, ahexadecyl group, an isohexadecyl group, a heptadecyl group, an octadecylgroup, a nonadecyl group, an icosyl group, a henicosyl group and adocosyl group.

The branched alkyl group preferably has 3 to 20 carbon atoms, morepreferably 3 to 15, and most preferably 3 to 10. Specific examplesinclude a 1-methylethyl group, a 1-methylpropyl group, a 2-methylpropylgroup, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutylgroup, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentylgroup, a 2-methylpentyl group, a 3-methylpentyl group and a4-methylpentyl group.

Chain alkenyl group which may have a substituent:

The chain-like alkenyl group for R¹⁰¹ may be linear or branched, andpreferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbonatoms, still more preferably 2 to 4 carbon atoms, and most preferably 3carbon atoms. Examples of linear alkenyl groups include a vinyl group, apropenyl group (an allyl group) and a butynyl group. Examples ofbranched alkenyl groups include a 1-methylvinyl group, a 2-methylvinylgroup, a 1-methylpropenyl group and a 2-methylpropenyl group.

Among these examples, as the chain-like alkenyl group, a linear alkenylgroup is preferable, a vinyl group or a propenyl group is morepreferable, and a vinyl group is most preferable.

As the substituent for the chain-like alkyl group or alkenyl group forR¹⁰¹, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxyl group, a carbonyl group, a nitro group, an amino group, acyclic group for R¹⁰¹ or the like can be used.

Among the above examples, as R¹⁰¹, a cyclic group which may have asubstituent is preferable, and a cyclic hydrocarbon group which may havea substituent is more preferable. Specifically, a phenyl group, anaphthyl group, a group in which one or more hydrogen atoms have beenremoved from a polycycloalkane, a lactone-containing cyclic grouprepresented by any one of the aforementioned formula (a2-r-1) to(a2-r-7), and an —SO₂— containing cyclic group represented by any one ofthe aforementioned formula (a5-r-1) to (a5-r-4).

In formula (b1-1-an1), Y¹⁰¹ represents a single bond or a divalentlinking group containing an oxygen atom.

In the case where Y¹⁰¹ is a divalent linking group containing an oxygenatom, Y¹⁰ 1 may contain an atom other than an oxygen atom. Examples ofatoms other than an oxygen atom include a carbon atom, a hydrogen atom,a sulfur atom and a nitrogen atom.

Examples of divalent linking groups containing an oxygen atom includenon-hydrocarbon, oxygen atom-containing linking groups such as an oxygenatom (an ether bond; —O—), an ester bond (—C(═O)—O—), an oxycarbonylgroup (—O—C(═O)—), an amido bond (—C(═O)—NH—), a carbonyl group(—C(═O)—) and a carbonate bond (—O—C(═O)—O—); and combinations of theaforementioned non-hydrocarbon, hetero atom-containing linking groupswith an alkylene group. Furthermore, the combinations may have asulfonyl group (—SO₂—) bonded thereto. Examples of divalent linkinggroups containing an oxygen atom include linking groups represented bygeneral formulae (y-a1-1) to (y-a1-7) shown below.

In the formulae, V′¹⁰¹ represents a single bond or an alkylene group of1 to 5 carbon atoms; V′¹⁰² represents a divalent saturated hydrocarbongroup of 1 to 30 carbon atoms.

The divalent saturated hydrocarbon group for V′¹⁰² is preferably analkylene group of 1 to 30 carbon atoms, more preferably an alkylenegroup of 1 to 10 carbon atoms, and still more preferably an alkylenegroup of 1 to 5 carbon atoms.

The alkylene group for V′¹⁰¹ and V′¹⁰² may be a linear alkylene group ora branched alkylene group, and a linear alkylene group is preferable.

Specific examples of the alkylene group for V′¹⁰¹ and V′¹⁰² include amethylene group [—CH₂—]; an alkylmethylene group, such as —CH(CH₃)—,—CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)— and—C(CH₂CH₃)₂—; an ethylene group [—CH₂CH₂—]; an alkylethylene group, suchas —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂— and —CH(CH₂CH₃)CH₂—; atrimethylene group (n-propylene group) [—CH₂CH₂CH₂—]; analkyltrimethylene group, such as —CH(CH₃)CH₂CH₂— and —CH₂CH(CH₃)CH₂—; atetramethylene group [—CH₂CH₂CH₂CH₂—]; an alkyltetramethylene group,such as —CH(CH₃)CH₂CH₂CH₂—, —CH₂CH(CH₃)CH₂CH₂—; and a pentamethylenegroup [—CH₂CH₂CH₂CH₂CH₂—].

Further, part of methylene group within the alkylene group for V′¹⁰¹ andV′¹⁰² may be substituted with a divalent aliphatic cyclic group of 5 to10 carbon atoms. The aliphatic cyclic group is preferably a divalentgroup in which one hydrogen atom has been removed from the cyclicaliphatic hydrocarbon group (monocyclic aliphatic hydrocarbon group orpolycyclic aliphatic hydrocarbon group) for Ra′³ in the aforementionedformula (a1-r-1), and a cyclohexylene group, 1,5-adamantylene group or2,6-adamantylene group is preferable.

Y¹⁰¹ is preferably a divalent linking group containing an ether bond ora divalent linking group containing an ester bond, and groupsrepresented by the aforementioned formulas (y-a1-1) to (y-a1-5) arepreferable.

In formula (b1-1-an1), V¹⁰¹ represents a single bond, an alkylene groupor a fluorinated alkylene group. The alkylene group and the fluorinatedalkylene group for V¹⁰¹ preferably has 1 to 4 carbon atoms. Examples ofthe fluorinated alkylene group for V¹⁰¹ include a group in which part orall of the hydrogen atoms within the alkylene group for V¹⁰¹ have beensubstituted with fluorine. Among these examples, as V¹⁰¹, a single bondor a fluorinated alkylene group of 1 to 4 carbon atoms is preferable.

In formula (b1-1-an1), R¹⁰² represents a fluorine atom or a fluorinatedalkyl group of 1 to 5 carbon atoms. R¹⁰² is preferably a fluorine atomor a perfluoroalkyl group of 1 to 5 carbon atoms, and more preferably afluorine atom.

As a specific example of the anion moiety represented by theaforementioned formula (b1-1-an1), in the case where Y¹⁰¹ a single bond,a fluorinated alkylsulfonate anion such as a trifluoromethanesulfonateanion or a perfluorobutanesulfonate anion can be mentioned; and in thecase where Y¹⁰¹ represents a divalent linking group containing an oxygenatom, anions represented by formulae (an-1) to (an-3) shown below can bementioned.

In the formulae, R″¹⁰¹ represents an aliphatic cyclic group which mayhave a substituent, a group represented by any one of the aforementionedformulas (r-hr-1) to (r-hr-6) or a chain-like alkyl group which may havea substituent; R″¹⁰² represents an aliphatic cyclic group which may havea substituent, a lactone-containing cyclic group represented by any oneof the aforementioned formulae (a2-r-1) to (a2-r-7) or an —SO₂—containing cyclic group represented by any one of the aforementionedformulae (a5-r-1) to (a5-r-4); R″¹⁰³ represents an aromatic cyclic groupwhich may have a substituent, an aliphatic cyclic group which may have asubstituent or a chain-like alkenyl group which may have a substituent;v″ represents an integer of 0 to 3; q″ represents an integer of 1 to 20;t″ represents an integer of 1 to 3; and n″ represents 0 or 1.

As the aliphatic cyclic group for R″¹⁰¹, R″¹⁰² and R″¹⁰³ which may havea substituent, the same groups as the cyclic aliphatic hydrocarbon groupfor R¹⁰¹ described above are preferable. As the substituent, the samegroups as those described above for substituting the cyclic aliphatichydrocarbon group for R¹⁰¹ can be mentioned.

As the aromatic cyclic group for R″¹⁰³ which may have a substituent, thesame groups as the aromatic hydrocarbon group for the cyclic hydrocarbongroup represented by R¹⁰¹ described above are preferable. Thesubstituent is the same as defined for the substituent for the aromatichydrocarbon group represented by R¹⁰¹.

As the chain-like alkyl group for R″¹⁰¹ which may have a substituent,the same groups as those described above for R¹⁰¹ are preferable. As thechain-like alkenyl group for R″¹⁰³ which may have a substituent, thesame groups as those described above for R¹⁰¹ are preferable.

Anion Represented by General Formula (b1-1-an2) In formula (b1-1-an2),R¹⁰⁴ and R¹⁰⁵ each independently represents a cyclic group which mayhave a substituent, a chain-like alkyl group which may have asubstituent or a chain-like alkenyl group which may have a substituent,and is the same as defined for R¹⁰¹ in formula (b1-1-an1). R¹⁰⁴ and R¹⁰⁵may be mutually bonded to form a ring.

As R¹⁰⁴ and R¹⁰⁵, a chain-like alkyl group which may have a substituentis preferable, and a linear or branched alkyl group or a linear orbranched fluorinated alkyl group is more preferable.

The chain-like alkyl group preferably has 1 to 10 carbon atoms, morepreferably 1 to 7 carbon atoms, and still more preferably 1 to 3 carbonatoms. The smaller the number of carbon atoms of the chain-like alkylgroup for R¹⁰⁴ and R¹⁰⁵, the more the solubility in a resist solvent isimproved. Further, in the chain-like alkyl group for R¹⁰⁴ and R¹⁰⁵, itis preferable that the number of hydrogen atoms substituted withfluorine atoms is as large as possible because the acid strengthincreases. The fluorination ratio of the chain-like alkyl group ispreferably from 70 to 100%, more preferably from 90 to 100%, and it isparticularly desirable that the chain-like alkyl group be aperfluoroalkyl group in which all hydrogen atoms are substituted withfluorine atoms.

In formula (b1-1-an2), V¹⁰² and V¹⁰³ each independently represents asingle bond, an alkylene group or a fluorinated alkylene group, and isthe same as defined for V¹⁰¹ in formula (b1-1-an1).

In formula (b1-1-an2), L¹⁰¹ and L¹⁰² each independently represents asingle bond or an oxygen atom.

Anion Represented by General Formula (b1-1-an3)

In formula (b1-1-an3), R¹⁰⁶ to R¹⁰⁸ each independently represents acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent or a chain-like alkenyl group which mayhave a substituent, and is the same as defined for R¹⁰¹ in formula(b1-1-an1).

In formula (b1-1-an3), L¹⁰³ to L¹⁰⁵ each independently represents asingle bond, —CO— or —SO₂—.

In the aforementioned formula (b1-1), X⁻ may be R¹⁰⁹—SO₃—. R¹⁰⁹represents a cyclic group which may have a substituent, a chain alkylgroup which may have a substituent, or a chain alkenyl group which mayhave a substituent, and is the same as defined for R¹⁰¹ in theaforementioned formula (b1-1-an1). However, in R¹⁰⁹, the carbon atomadjacent to the S atom has a fluorine atom bonded thereto.

Alternatively, in the aforementioned formula (b1-1), X⁻ may be a halogenanion. Examples of the halogen anion include a fluoride ion, a chlorideion, a bromide ion and an iodide ion.

Among these examples, as the anion moiety of the component (B1), ananion represented by general formula (b1-1-an1) is preferable. Amongthese, an anion represented by any one of the aforementioned generalformulae (an-1) to (an-3) is more preferable, and an anion representedby the aforementioned general formula (an-1) or (an-2) is morepreferable.

Preferable examples of the component (B1) include a combination of ananion represented by any one of the aforementioned formulae (b1-1-an1)to (b1-1-an3) (more preferably an anion represented by any one ofgeneral formulae (an-1) to (an-3)) with a cation represented by any oneof formulae (ca-01-1) to (ca-01-38). Specific examples of the component(B1) are shown below, although the component (B1) is not limited tothese examples.

In the resist composition of the present embodiment, as the component(B1), one kind of compound may be used, or two or more kinds ofcompounds may be used in combination.

In the resist composition of the present embodiment, the amount of thecomponent (B1) relative to 100 parts by weight of the component (A) ispreferably within a range from 5 to 65 parts by weight, more preferablyfrom 5 to 55 parts by weight, still more preferably from 10 to 45 partsby weight, and most preferably 10 to 40 parts by weight.

In the resist composition, the amount of the component (B1) within theentire component (B) capable of generating acid which acts on thecomponent (A) is, for example, 50% by weight or more, preferably 70% byweight or more, and more preferably 95% by weight or more. The amount ofthe component (B1) within the component (B) may be even 100% by weight.

When the amount of the component (B1) is at least as large as the lowerlimit of the above-mentioned preferable range, in the formation of aresist pattern, sensitivity and various lithography properties such asline width roughness (LWR) and pattern shape are improved. On the otherhand, in the case where the amount of the component (B1) is no more thanthe upper limit of the above-mentioned preferable range, when each ofthe components of the resist composition are dissolved in an organicsolvent, a homogeneous solution may be more reliably obtained and thestorage stability of the resist composition becomes satisfactory.

<<Component (B2)>>

The resist composition of the present embodiment may contain an acidgenerator other than the component (B1) (hereafter, referred to as“component (B2)”), as long as the effects of the present invention arenot impaired.

As the component (B2), there is no particular limitation, and any of theknown acid generators used in conventional chemically amplified resistcompositions may be used.

Examples of these acid generators are numerous, and include onium saltacid generators such as iodonium salts and sulfonium salts; oximesulfonate acid generators; diazomethane acid generators such as bisalkylor bisaryl sulfonyl diazomethanes and poly(bis-sulfonyl)diazomethanes;nitrobenzylsulfonate acid generators; iminosulfonate acid generators;and disulfone acid generators.

As the onium salt acid generator, a compound represented by generalformula (b-1) below (hereafter, sometimes referred to as “component(b-1)”), a compound represented by general formula (b-2) below(hereafter, sometimes referred to as “component (b-2)”) or a compoundrepresented by general formula (b-3) below (hereafter, sometimesreferred to as “component (b-3)”) may be mentioned. However, thecomponent (b-1) does not include compounds which fall under the categoryof the component (B1).

In the formulae, R¹⁰¹ and R¹⁰⁴ to R¹⁰⁸ each independently represents acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent or a chain-like alkenyl group which mayhave a substituent, provided that R¹⁰⁴ and R¹⁰⁵ may be mutually bondedto form a ring; R¹⁰² represents a fluorine atom or a fluorinated alkylgroup of 1 to 5 carbon atoms; Y¹⁰¹ represents a single bond or adivalent linking group containing an oxygen atom; V¹⁰¹ to V¹⁰³ eachindependently represents a single bond, an alkylene group or afluorinated alkylene group; L¹⁰¹ and L¹⁰² each independently representsa single bond or an oxygen atom; L¹⁰³ to L¹⁰⁵ each independentlyrepresents a single bond, —CO— or —SO₂—; and m represents an integer of1 or more; and M′^(m+) represents an m-valent onium cation.

In formulae (b-1), (b-2) and (b-3), R¹⁰¹ and R¹⁰⁴ to R¹⁰⁸ are the sameas defined for R¹⁰¹ and R¹⁰⁴ to R¹⁰⁸ in the aforementioned formulae(b1-1-an1) to (b1-1-an3), respectively.

In formulae (b-1), (b-2) and (b-3), R¹⁰⁴ and R¹⁰⁵ are the same asdefined for R¹⁰⁴ and R¹⁰⁵ in the aforementioned formulae (b1-1-an1) to(b1-1-an3), respectively.

In formulae (b-1), (b-2) and (b-3), Y¹⁰¹ is the same as defined for Y¹⁰¹in the aforementioned formulae (b1-1-an1) to (b1-1-an3).

In formulae (b-1), (b-2) and (b-3), V¹⁰¹ to V¹⁰³ are the same as definedfor V¹⁰¹ to V¹⁰³ in the aforementioned formulae (b1-1-an1) to(b1-1-an3), respectively.

In formulae (b-1), (b-2) and (b-3), L¹⁰¹ and L¹⁰² are the same asdefined for L¹⁰¹ and L¹⁰² in the aforementioned formulae (b1-1-an1) to(b1-1-an3), respectively.

In formulae (b-1), (b-2) and (b-3), L¹⁰³ to L¹⁰⁵ are the same as definedfor L¹⁰³ to L¹⁰⁵ in the aforementioned formulae (b1-1-an1) to(b1-1-an3), respectively.

In formulae (b-1), (b-2), and (b-3), m represents an integer of 1 orgreater, M′^(m+) represents an m-valent onium cation, and preferableexamples thereof include a sulfonium cation and an iodonium cation.

Preferable examples of the cation moiety ((M′^(m+))/m) include anorganic cation represented by any of general formulae (ca-1) to (ca-4)shown below. However, cations which fall under the definition of thecation moiety of the compound represented by general formula (b1) areexcluded.

In the formulae, R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² each independentlyrepresents an aryl group which may have a substituent, an alkyl groupwhich may have a substituent, or an alkenyl group which may have asubstituent. R²⁰¹ to R²⁰³, R²⁰⁶ and R²⁰⁷, and R²¹¹ and R²¹² may bemutually bonded to form a ring with the sulfur atom. R²⁰⁸ and R²⁰⁹ eachindependently represents a hydrogen atom or an alkyl group of 1 to 5carbon atoms. R²¹⁰ represents an aryl group which may have asubstituent, an alkyl group which may have a substituent, an alkenylgroup which may have a substituent, or an —SO₂— containing cyclic groupwhich may have a substituent. L²⁰¹ represents —C(═O)— or —C(═O)—O—. EachY²⁰¹ independently represents an arylene group, an alkylene group or analkenylene group. x represents 1 or 2. W²⁰¹ represents an (x+1) valentlinking group.

The aryl group represented by R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² is the same asdefined for the aryl group represented by R^(b1) in the aforementionedformula (b1).

The alkyl group represented by R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² is the sameas the alkyl group represented by R^(b2) and R^(b3) in theaforementioned formula (b1).

The alkenyl group for R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² preferably has 2 to 10carbon atoms.

Specific examples of the substituent which R²⁰¹ to R²⁰⁷ and R²¹⁰ to R²¹²may have include an alkyl group, a halogen atom, a halogenated alkylgroup, a carbonyl group, a cyano group, an amino group, an aryl group,and groups represented by the aforementioned general formulae (ca-r-1)to (ca-r-7).

In the case where R²⁰¹ to R²⁰³, R²⁰⁶ and R²⁰⁷ or R²¹¹ and R²¹² aremutually bonded to form a ring with the sulfur atom, the ring is thesame as defined for the case where R^(b2) and R^(b3) in theaforementioned formula (b1) are mutually bonded to form a ring with thesulfur atom.

R²⁰⁸ and R²⁰⁹ each independently represents a hydrogen atom or an alkylgroup of 1 to 5 carbon atoms, preferably a hydrogen atom or an alkylgroup of 1 to 3 carbon atoms, and when R²⁰⁸ and R²⁰⁹ each represents analkyl group, R²⁰⁸ and R²⁰⁹ may be mutually bonded to form a ring.

R²¹⁰ represents an aryl group which may have a substituent, an alkylgroup which may have a substituent, an alkenyl group which may have asubstituent, or an —SO₂— containing cyclic group which may have asubstituent.

Examples of the aryl group for R²¹⁰ include an unsubstituted aryl groupof 6 to 20 carbon atoms, and a phenyl group or a naphthyl group ispreferable.

As the alkyl group for R²¹⁰, a chain-like or cyclic alkyl group having 1to 30 carbon atoms is preferable.

The alkenyl group for R²¹⁰ preferably has 2 to 10 carbon atoms.

As the —SO₂— containing cyclic group for R²¹⁰ which may have asubstituent, an “—SO₂— containing polycyclic group” is preferable, and agroup represented by the aforementioned general formula (a5-r-1) is morepreferable.

Each Y²⁰¹ independently represents an arylene group, an alkylene groupor an alkenylene group.

Examples of the arylene group for Y²⁰¹ include groups in which onehydrogen atom has been removed from an aryl group given as an example ofthe aromatic hydrocarbon group for R¹⁰¹ in the aforementioned formula(b1-1-an1).

Examples of the alkylene group and alkenylene group for Y²⁰¹ includegroups in which one hydrogen atom has been removed from the chain-likealkyl group or the chain-like alkenyl group given as an example of R¹⁰¹in the aforementioned formula (b1-1-an1).

In the formula (ca-4), x represents 1 or 2.

W²⁰¹ represents a linking group having a valency of (x+1), i.e., adivalent or trivalent linking group.

As the divalent linking group for W²⁰¹, a divalent hydrocarbon groupwhich may have a substituent is preferable, and as examples thereof, thesame hydrocarbon groups (which may have a substituent) as thosedescribed above for Ya²¹ in the general formula (a2-1) can be mentioned.The divalent linking group for W²⁰¹ may be linear, branched or cyclic,and cyclic is more preferable. Among these, an arylene group having twocarbonyl groups, each bonded to the terminal thereof is preferable.Examples of the arylene group include a phenylene group and anaphthylene group, and a phenylene group is particularly desirable.

As the trivalent linking group for W²⁰¹, a group in which one hydrogenatom has been removed from the aforementioned divalent linking group forW²⁰¹ and a group in which the divalent linking group has been bonded toanother divalent linking group can be mentioned. The trivalent linkinggroup for W²⁰¹ is preferably a group in which 2 carbonyl groups arebonded to an arylene group.

Specific examples of preferable cations represented by formula (ca-1)include cations represented by formulae (ca-1-1) to (ca-1-71) shownbelow.

In the formulae, g1, g2 and g3 represent recurring numbers, wherein g1is an integer of 1 to 5, g2 is an integer of 0 to 20, and g3 is aninteger of 0 to 20.

In the formulae, R″²⁰¹ represents a hydrogen atom or a substituent, andas the substituent, the same groups as those described above forsubstituting R²⁰¹ to R²⁰⁷ and R²¹⁰ to R²¹² can be mentioned.

Specific examples of preferable cations represented by the formula(ca-2) include a dihphenyliodonium cation and abis(4-tert-butylphenyl)iodonium cation.

Specific examples of preferable cations represented by formula (ca-3)include cations represented by formulae (ca-3-1) to (ca-3-6) shownbelow.

Specific examples of preferable cations represented by formula (ca-4)include cations represented by formulae (ca-4-1) and (ca-4-2) shownbelow.

Among the above examples, as the cation moiety ((M′^(m+))_(1/m)), acation represented by general formula (ca-1) is preferable, and a cationrepresented by any one of formulae (ca-1-1) to (ca-1-71) is morepreferable.

In the resist composition of the present embodiment, as the component(B2), one kind of compound may be used, or two or more kinds ofcompounds may be used in combination.

When the resist composition contains the component (B2), the amount ofthe component (B2) relative to 100 parts by weight of the component (A)is preferably 50 parts by weight or less, more preferably 1 to 40 partsby weight, and still more preferably 5 to 30 parts by weight.

When the amount of the component (B2) is within the above-mentionedrange, formation of a resist pattern may be satisfactorily performed.

<<Acid Diffusion Control Agent (D)>>

The resist composition according to the present embodiment may includean acid diffusion control agent component (hereafter, sometimes referredto as “component (D)”), in addition to the component (A), or in additionto the component (A) and the component (B). The component (D) functionsas an acid diffusion control agent, i.e., a quencher which traps theacid generated in the resist composition upon exposure.

The component (D) may be a photodecomposable base (D1) (hereafter,referred to as “component (D1)”) which is decomposed upon exposure andthen loses the ability of controlling of acid diffusion, or anitrogen-containing organic compound (D2) (hereafter, referred to as“component (D2)”) which does not fall under the definition of component(D1).

Component (D1)

When a resist pattern is formed using a resist composition containingthe component (D1), the contrast between exposed portions and unexposedportions of the resist film is improved.

The component (D1) is not particularly limited, as long as it isdecomposed upon exposure and then loses the ability of controlling ofacid diffusion. As the component (D1), at least one compound selectedfrom the group consisting of a compound represented by general formula(d1-1) shown below (hereafter, referred to as “component (d1-1)”), acompound represented by general formula (d1-2) shown below (hereafter,referred to as “component (d1-2)”) and a compound represented by generalformula (d1-3) shown below (hereafter, referred to as “component(d1-3)”) is preferably used.

At exposed portions of the resist film, the components (d1-1) to (d1-3)are decomposed and then lose the ability of controlling of aciddiffusion (i.e., basicity), and therefore the components (d1-1) to(d1-3) cannot function as a quencher, whereas at unexposed portions, thecomponents (d1-1) to (d1-3) functions as a quencher.

In the formulae, Rd¹ to Rd⁴ represent a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, provided that,the carbon atom adjacent to the sulfur atom within the Rd² in theformula (d1-2) has no fluorine atom bonded thereto; Yd¹ represents asingle bond or a divalent linking group; m represents an integer of 1 ormore; and each M^(m+) independently represents an organic cation havinga valency of m.

Cation Moiety

In the aforementioned formulae, each M^(m+) independently represents am-valent organic cation.

In the present specification, regarding the m-valent organic cation informulae (d1-1) to (d1-3), a component (D1) which has the same cation asin general formula (b1) is sometimes referred to as component (D11).

A component (D1) which does not have the same cation as in generalformula (b1) is sometimes referred to as component (D12).

In the resist composition of the present embodiment, as the component(D1), either of the component (D11) and the component (D12) may be usedalone, or two or more kinds may be used.

Examples of the m-valent organic cation represented by M^(m+) includethe same organic cation as the cation moiety in the aforementionedgeneral formula (b1), and an organic cation represented by theaforementioned general formulae (ca-1) to (ca-4).

{Component (d1-1)}

Anion Moiety

In formula (d1-1), Rd¹ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹ in the aforementioned formula(b-1).

Among these, as the group for Rd¹, an aromatic hydrocarbon group whichmay have a substituent, an aliphatic cyclic group which may have asubstituent and a chain-like alkyl group which may have a substituentare preferable. Examples of the substituent for these groups include ahydroxy group, an oxo group, an alkyl group, an aryl group, a fluorineatom, a fluorinated alkyl group, a lactone-containing cyclic grouprepresented by any one of the aforementioned formulae (a2-r-1) to(a2-r-7), an ether bond, an ester bond, and a combination thereof. Inthe case where an ether bond or an ester bond is included as thesubstituent, the substituent may be bonded via an alkylene group, and alinking group represented by any one of the aforementioned formulae(y-a1-1) to (y-a1-5) is preferable as the substituent.

Preferable examples of the aromatic hydrocarbon group include a phenylgroup, a naphthyl group, and a polycyclic structure (for example, apolycyclic structure formed of a ring structure having a bicyclooctaneskeleton and a ring structure other than the bicyclooctane skeleton)containing a bicyclooctane skeleton.

Examples of the aliphatic cyclic group include groups in which one ormore hydrogen atoms have been removed from a polycycloalkane such asadamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane.

The chain-like alkyl group preferably has 1 to 10 carbon atoms, andspecific examples thereof include a linear alkyl group such as a methylgroup, an ethyl group, a propyl group, a butyl group, a pentyl group, ahexyl group, a heptyl group, an octyl group, a nonyl or a decyl group,and a branched alkyl group such as a 1-methylethyl group, a1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a3-methylpentyl group or a 4-methylpentyl group.

In the case where the chain-like alkyl group is a fluorinated alkylgroup having a fluorine atom or a fluorinated alkyl group, thefluorinated alkyl group preferably has 1 to 11 carbon atoms, morepreferably 1 to 8 carbon atoms, and still more preferably 1 to 4 carbonatoms. The fluorinated alkyl group may contain an atom other thanfluorine. Examples of the atom other than fluorine include an oxygenatom, a sulfur atom and a nitrogen atom.

As Rd¹, a fluorinated alkyl group in which part or all of the hydrogenatoms constituting a linear alkyl group have been substituted withfluorine atom(s) is preferable, and a fluorinated alkyl group in whichall of the hydrogen atoms constituting a linear alkyl group have beensubstituted with fluorine atoms (i.e., a linear perfluoroalkyl group) isparticularly desirable.

Specific examples of preferable anion moieties for the component (d1-1)are shown below.

As the component (d1-1), one kind of compound may be used, or two ormore kinds of compounds may be used in combination.

{Component (d1-2)}

Anion Moiety

In formula (d1-2), Rd² represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹ in the aforementioned formula(b-1).

However, the carbon atom adjacent to the sulfur atom within Rd² grouphas no fluorine atom bonded thereto (i.e., the carbon atom adjacent tothe sulfur atom within Rd² group does not substituted with a fluorineatom). As a result, the anion of the component (d1-2) becomes anappropriately weak acid anion, thereby improving the quenching abilityof the component (D).

As Rd², a chain-like alkyl group which may have a substituent or analiphatic cyclic group which may have a substituent is preferable. Thechain-like alkyl group preferably has 1 to 10 carbon atoms, and morepreferably 3 to 10 carbon atoms. As the aliphatic cyclic group, a groupin which one or more hydrogen atoms have been removed from adamantane,norbornane, isobornane, tricyclodecane, tetracyclododecane or camphor(which may have a substituent) is more preferable.

The hydrocarbon group for Rd² may have a substituent. As thesubstituent, the same groups as those described above for substitutingthe hydrocarbon group (e.g., aromatic hydrocarbon group, aliphaticcyclic group, chain-like alkyl group) for Rd¹ in the formula (d1-1) canbe mentioned.

Specific examples of preferable anion moieties for the component (d1-2)are shown below.

As the component (d1-2), one type of compound may be used, or two ormore types of compounds may be used in combination.

{Component (d1-3)}

Anion Moiety

In formula (d1-3), Rd³ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹ in the aforementioned formula(b-1), and a cyclic group containing a fluorine atom, a chain-like alkylgroup or a chain-like alkenyl group is preferable. Among these, afluorinated alkyl group is preferable, and more preferably the samefluorinated alkyl groups as those described above for Rd¹.

In formula (d1-3), Rd⁴ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹ in the aforementioned formula(b-1).

Among these, an alkyl group which may have substituent, an alkoxy groupwhich may have substituent, an alkenyl group which may have substituentor a cyclic group which may have substituent is preferable.

The alkyl group for Rd⁴ is preferably a linear or branched alkyl groupof 1 to 5 carbon atoms, and specific examples include a methyl group, anethyl group, a propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a tert-butyl group, a pentyl group, an isopentyl group,and a neopentyl group. Part of the hydrogen atoms within the alkyl groupfor Rd⁴ may be substituted with a hydroxy group, a cyano group or thelike.

The alkoxy group for Rd⁴ is preferably an alkoxy group of 1 to 5 carbonatoms, and specific examples thereof include a methoxy group, an ethoxygroup, an n-propoxy group, an iso-propoxy group, an n-butoxy group and atert-butoxy group. Among these, a methoxy group and an ethoxy group arepreferable.

As the alkenyl group for Rd⁴, the same groups as those described abovefor R¹⁰¹ in the aforementioned formula (b-1) can be mentioned, and avinyl group, a propenyl group (an allyl group), a 1-methylpropenyl groupand a 2-methylpropenyl group are preferable. These groups may have analkyl group of 1 to 5 carbon atoms or a halogenated alkyl group of 1 to5 carbon atoms as a substituent.

As the cyclic group for Rd⁴, the same groups as those described abovefor R¹⁰¹ in the aforementioned formula (b-1) can be mentioned. Amongthese, as the cyclic group, an alicyclic group (e.g., a group in whichone or more hydrogen atoms have been removed from a cycloalkane such ascyclopentane, cyclohexane, adamantane, norbornane, isobornane,tricyclodecane or tetracyclododecane) or an aromatic group (e.g., aphenyl group or a naphthyl group) is preferable. When Rd⁴ is analicyclic group, the resist composition can be satisfactorily dissolvedin an organic solvent, thereby improving the lithography properties.

In formula (d1-3), Yd¹ represents a single bond or a divalent linkinggroup.

The divalent linking group for Yd¹ is not particularly limited, andexamples thereof include a divalent hydrocarbon group (aliphatichydrocarbon group, or aromatic hydrocarbon group) which may have asubstituent and a divalent linking group containing a hetero atom. Thedivalent linking groups are the same as defined for the divalenthydrocarbon group which may have a substituent and the divalent linkinggroup containing a hetero atom explained above as the divalent linkinggroup for Ya²¹ in the aforementioned formula (a2-1).

As Yd¹, a carbonyl group, an ester bond, an amide bond, an alkylenegroup or a combination of these is preferable. As the alkylene group, alinear or branched alkylene group is more preferable, and a methylenegroup or an ethylene group is still more preferable.

Specific examples of preferable anion moieties for the component (d1-3)are shown below.

As the component (d1-3), one type of compound may be used, or two ormore types of compounds may be used in combination.

As the component (D1), one type of the aforementioned components (d1-1)to (d1-3), or at least two types of the aforementioned components (d1-1)to (d1-3) can be used in combination.

When the resist composition contains the component (D1), the amount ofthe component (D1) relative to 100 parts by weight of the component (A)is preferably within a range from 0.5 to 35 parts by weight, morepreferably from 1 to 25 parts by weight, and still more preferably from2 to 20 parts by weight.

When the amount of the component (D1) is at least as large as the lowerlimit of the above-mentioned range, excellent lithography properties andexcellent resist pattern shape can be more reliably obtained. On theother hand, when the amount of the component (D1) is no more than theupper limit of the above-mentioned range, sensitivity can be maintainedat a satisfactory level, and through-put becomes excellent.

Production Method of Component (D1):

The production methods of the components (d1-1) and (d1-2) are notparticularly limited, and the components (d1-1) and (d1-2) can beproduced by conventional methods.

Further, the production method of the component (d1-3) is notparticularly limited, and the component (d1-3) can be produced in thesame manner as disclosed in US2012-0149916.

Component (D2)

The acid diffusion control component may contain a nitrogen-containingorganic compound (D2) (hereafter, referred to as component (D2)) whichdoes not fall under the definition of component (D1).

The component (D2) is not particularly limited, as long as it functionsas an acid diffusion control agent, and does not fall under thedefinition of the component (D1). As the component (D2), any of theconventionally known compounds may be selected for use. Among these, analiphatic amine is preferable, and a secondary aliphatic amine ortertiary aliphatic amine is more preferable.

An aliphatic amine is an amine having one or more aliphatic groups, andthe aliphatic groups preferably have 1 to 12 carbon atoms.

Examples of these aliphatic amines include amines in which at least onehydrogen atom of ammonia (NH₃) has been substituted with an alkyl groupor hydroxyalkyl group of no more than 12 carbon atoms (i.e., alkylaminesor alkylalcoholamines), and cyclic amines.

Specific examples of alkylamines and alkylalcoholamines includemonoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine,n-nonylamine, and n-decylamine; dialkylamines such as diethylamine,di-n-propylamine, di-n-heptylamine, di-n-octylamine, anddicyclohexylamine; trialkylamines such as trimethylamine, triethylamine,tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine,tri-n-pentylamine, tri-n-heptylamine, tri-n-octylamine,tri-n-nonylamine, tri-n-decylamine, and tri-n-dodecylamine; and alkylalcohol amines such as diethanolamine, triethanolamine,diisopropanolamine, triisopropanolamine, di-n-octanolamine, andtri-n-octanolamine. Among these, trialkylamines of 5 to 10 carbon atomsare preferable, and tri-n-pentylamine and tri-n-octylamine areparticularly desirable.

Examples of the cyclic amine include heterocyclic compounds containing anitrogen atom as a hetero atom. The heterocyclic compound may be amonocyclic compound (aliphatic monocyclic amine), or a polycycliccompound (aliphatic polycyclic amine).

Specific examples of the aliphatic monocyclic amine include piperidine,and piperazine.

The aliphatic polycyclic amine preferably has 6 to 10 carbon atoms, andspecific examples thereof include 1, 5-diazabicyclo[4.3.0]-5-nonene,1,8-diazabicyclo[5.4.0]-7-undecene, hexamethylenetetramine, and1,4-diazabicyclol[2.2.2]octane.

Examples of other aliphatic amines includetris(2-methoxymethoxyethyl)amine, tris{2-(2-methoxyethoxy)ethyl}amine,tris{2-(2-methoxyethoxymethoxy)ethyl}amine,tris{2-(1-methoxyethoxy)ethyl}amine, tris{2-(1-ethoxyethoxy)ethyl}amine,tris{2-(1-ethoxypropoxy)ethyl}amine,tris[2-{2-(2-hydroxyethoxy)ethoxy}ethyl]amine and triethanolaminetriacetate, and triethanolamine triacetate is preferable.

Further, as the component (D2), an aromatic amine may be used.

Examples of aromatic amines include 4-dimethylaminopyridine, pyrrole,indole, pyrazole, imidazole and derivatives thereof, as well astribenzylamine, 2,6-diisopropylaniline andN-tert-butoxycarbonylpyrrolidine.

As the component (D2), one type of compound may be used alone, or two ormore types may be used in combination.

When the resist composition contains the component (D2), the amount ofthe component (D2) is typically used in an amount within a range from0.01 to 5 parts by weight, relative to 100 parts by weight of thecomponent (A). When the amount of the component (D) is within theabove-mentioned range, the shape of the resist pattern and the postexposure stability of the latent image formed by the pattern-wiseexposure of the resist layer are improved.

<<Component (E): At Least One Compound Selected from the GroupConsisting of Organic Carboxylic Acids, and Phosphorus Oxo Acids andDerivatives Thereof>>

In the resist composition of the present embodiment, for preventing anydeterioration in sensitivity, and improving the resist pattern shape andthe post exposure stability of the latent image formed by thepattern-wise exposure of the resist layer, at least one compound (E)(hereafter referred to as the component (E)) selected from the groupconsisting of an organic carboxylic acid, or a phosphorus oxo acid orderivative thereof may be added.

Examples of suitable organic carboxylic acids include acetic acid,malonic acid, citric acid, malic acid, succinic acid, benzoic acid, andsalicylic acid.

Examples of phosphorus oxo acids include phosphoric acid, phosphonicacid and phosphinic acid. Among these, phosphonic acid is particularlydesirable.

Examples of oxo acid derivatives include esters in which a hydrogen atomwithin the above-mentioned oxo acids is substituted with a hydrocarbongroup. Examples of the hydrocarbon group include an alkyl group of 1 to5 carbon atoms and an aryl group of 6 to 15 carbon atoms.

Examples of phosphoric acid derivatives include phosphoric acid esterssuch as di-n-butyl phosphate and diphenyl phosphate.

Examples of phosphonic acid derivatives include phosphonic acid esterssuch as dimethyl phosphonate, di-n-butyl phosphonate, phenylphosphonicacid, diphenyl phosphonate and dibenzyl phosphonate.

Examples of phosphinic acid derivatives include phosphinic acid estersand phenylphosphinic acid.

In the resist composition of the present embodiment, as the component(E), one kind of compound may be used, or two or more kinds of compoundsmay be used in combination.

When the resist composition contains the component (E), the amount ofthe component (E) is typically used in an amount within a range from0.01 to 5 parts by weight, relative to 100 parts by weight of thecomponent (A).

<<Component (F): Fluorine Additive>>

In the present embodiment, the resist composition may further include afluorine additive (hereafter, referred to as “component (F)”) forimparting water repellency to the resist film, or improving lithographyproperties.

As the component (F), for example, a fluorine-containing polymericcompound described in Japanese Unexamined Patent Application, FirstPublication No. 2010-002870, Japanese Unexamined Patent Application,First Publication No. 2010-032994, Japanese Unexamined PatentApplication, First Publication No. 2010-277043, Japanese UnexaminedPatent Application, First Publication No. 2011-13569, and JapaneseUnexamined Patent Application, First Publication No. 2011-128226 can beused.

Specific examples of the component (F) include polymers having astructural unit (f1) represented by general formula (f1-1) shown below.As the polymer, a polymer (homopolymer) consisting of a structural unit(f1) represented by formula (f1-1) shown below; a copolymer of thestructural unit (f1) and the aforementioned structural unit (a1); and acopolymer of the structural unit (f1), a structural unit derived fromacrylic acid or methacrylic acid and the aforementioned structural unit(a1) are preferable. As the structural unit (a1) to be copolymerizedwith the structural unit (f1), a structural unit derived from1-ethyl-1-cyclooctyl (meth)acrylate or a structural unit derived from1-methyl-1-adamantyl (meth)acrylate is preferable.

In the formula, R is the same as defined above: Rf¹⁰² and Rf¹⁰³ eachindependently represents a hydrogen atom, a halogen atom, an alkyl groupof 1 to 5 carbon atoms, or a halogenated alkyl group of 1 to 5 carbonatoms, provided that Rf¹⁰² and Rf¹⁰³ may be the same or different; nf¹represents an integer of 1 to 5; and Rf¹⁰¹ represents an organic groupcontaining a fluorine atom.

In formula (f1-1), R bonded to the carbon atom on the α-position is thesame as defined above. As R, a hydrogen atom or a methyl group ispreferable.

In formula (f1-1), examples of the halogen atom for Rf¹⁰² and Rf¹⁰³include a fluorine atom, a chlorine atom, a bromine atom and an iodineatom, and a fluorine atom is particularly desirable. Examples of thealkyl group of 1 to 5 carbon atoms for Rf¹⁰² and Rf¹⁰³ include the samealkyl group of 1 to 5 carbon atoms as those described above for R, and amethyl group or an ethyl group is preferable. Specific examples of thehalogenated alkyl group of 1 to 5 carbon atoms represented by Rf¹⁰² orRf¹⁰³ include groups in which part or all of the hydrogen atoms of theaforementioned alkyl groups of 1 to 5 carbon atoms have been substitutedwith halogen atoms.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom, and a fluorine atom is particularlydesirable. Among these examples, as Rf¹⁰² and Rf¹⁰³, a hydrogen atom, afluorine atom or an alkyl group of 1 to 5 carbon atoms is preferable,and a hydrogen atom, a fluorine atom, a methyl group or an ethyl groupis more preferable.

In formula (f1-1), nf¹ represents an integer of 1 to 5, preferably aninteger of 1 to 3, and more preferably 1 or 2.

In formula (f1-1), Rf¹⁰¹ represents an organic group containing afluorine atom, and is preferably a hydrocarbon group containing afluorine atom.

The hydrocarbon group containing a fluorine atom may be linear, branchedor cyclic, and preferably has 1 to 20 carbon atoms, more preferably 1 to15 carbon atoms, and most preferably 1 to 10 carbon atoms.

It is preferable that the hydrocarbon group having a fluorine atom has25% or more of the hydrogen atoms within the hydrocarbon groupfluorinated, more preferably 50% or more, and most preferably 60% ormore, as the hydrophobicity of the resist film during immersion exposureis enhanced.

Among these, as Rf¹⁰¹, a fluorinated hydrocarbon group of 1 to 6 carbonatoms is preferable, and a trifluoromethyl group, —CH₂—CF₃,—CH₂—CF₂—CF₃, —CH(CF₃)₂, —CH₂—CH₂—CF₃, and —CH₂—CH₂—CF₂—CF₂—CF₂—CF₃ aremost preferable.

The weight average molecular weight (Mw) (the polystyrene equivalentvalue determined by gel permeation chromatography) of the component (F)is preferably 1,000 to 50,000, more preferably 5,000 to 40,000, and mostpreferably 10,000 to 30,000. When the weight average molecular weight(Mw) is no more than the upper limit of the above-mentioned range, theresist may exhibit satisfactory solubility in a resist solvent. On theother hand, when the weight average molecular weight (Mw) is at least aslarge as the lower limit of the above-mentioned range, the waterrepellency of the resist film may become satisfactory.

Further, the dispersity (Mw/Mn) of the component (F) is preferably 1.0to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5.

In the resist composition of the present embodiment, as the component(F), one kind of compound may be used, or two or more kinds of compoundsmay be used in combination.

When the resist composition contains the component (F), the component(F) is used in an amount within a range from 0.5 to 10 parts by weight,relative to 100 parts by weight of the component (A).

<<Component (S): Organic Solvent>>

The resist composition of the present embodiment may be prepared bydissolving the resist materials for the resist composition in an organicsolvent (hereafter, referred to as “component (S)”).

The component (S) may be any organic solvent which can dissolve therespective components to give a homogeneous solution, and any organicsolvent can be appropriately selected from those which have beenconventionally known as solvents for a chemically amplified resistcomposition.

Examples thereof include lactones such as y-butyrolactone; ketones suchas acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentyl ketone,methyl isopentyl ketone, and 2-heptanone; polyhydric alcohols, such asethylene glycol, diethylene glycol, propylene glycol and dipropyleneglycol; compounds having an ester bond, such as ethylene glycolmonoacetate, diethylene glycol monoacetate, propylene glycolmonoacetate, and dipropylene glycol monoacetate; polyhydric alcoholderivatives including compounds having an ether bond, such as amonoalkylether (e.g., monomethylether, monoethylether, monopropyletheror monobutylether) or monophenylether of any of these polyhydricalcohols or compounds having an ester bond (among these, propyleneglycol monomethyl ether acetate (PGMEA) and propylene glycol monomethylether (PGME) are preferable); cyclic ethers such as dioxane; esters suchas methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate,butyl acetate, methyl pyruvate, ethyl pyruvate, methylmethoxypropionate, and ethyl ethoxypropionate; aromatic organic solventssuch as anisole, ethylbenzylether, cresylmethylether, diphenylether,dibenzylether, phenetole, butylphenylether, ethylbenzene,diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymeneand mesitylene; and dimethylsulfoxide (DMSO).

In the resist composition of the present embodiment, as the component(S), one kind of solvent may be used, or two or more kinds of compoundsmay be used as a mixed solvent.

Among these, PGMEA, PGME, γ-butyrolactone, EL and cyclohexanone arepreferable.

Further, among the mixed solvents, a mixed solvent obtained by mixingPGMEA with a polar solvent is preferable. The mixing ratio (weightratio) of the mixed solvent can be appropriately determined, taking intoconsideration the compatibility of the PGMEA with the polar solvent, butis preferably in the range of 1:9 to 9:1, more preferably from 2:8 to8:2.

Specifically, when EL or cyclohexanone is mixed as the polar solvent,the PGMEA:EL or cyclohexanone weight ratio is preferably from 1:9 to9:1, and more preferably from 2:8 to 8:2. Alternatively, when PGME ismixed as the polar solvent, the PGMEA:PGME weight ratio is preferablyfrom 1:9 to 9:1, more preferably from 2:8 to 8:2, and still morepreferably 3:7 to 7:3. Furthermore, a mixed solvent of PGMEA, PGME andcyclohexanone is also preferable.

Further, as the component (S), a mixed solvent of at least one of PGMEAand EL with γ-butyrolactone is also preferable. The mixing ratio(former:latter) of such a mixed solvent is preferably from 70:30 to95:5.

The amount of the component (S) is not particularly limited, and isappropriately adjusted to a concentration which enables coating of acoating solution to a substrate. In general, the component (S) is usedin an amount such that the solid content of the resist compositionbecomes within the range from 0.1 to 20% by weight, and preferably from0.2 to 15% by weight.

If desired, other miscible additives can also be added to the resistcomposition of the present invention. Examples of such miscibleadditives include additive resins for improving the performance of theresist film, dissolution inhibitors, plasticizers, stabilizers,colorants, halation prevention agents, and dyes.

After dissolving the resist materials in the organic solvent (S), theresist composition of the present embodiment may have impurities or thelike removed by using a polyimide porous film, a polyamide-imide porousfilm, or the like. For example, the resist composition may be subjectedto filtration using a filter formed of a polyimide porous membrane, afilter formed of a polyamide-imide porous film, or a filter formed of apolyimide porous membrane and a polyamide-imide porous film. Examples ofthe polyimide porous membrane and the polyamide-imide porous filminclude those described in Japanese Unexamined Patent Application, FirstPublication No. 2016-155121.

The resist composition according to the present embodiment describedabove includes an acid generator (B1) containing a compound representedby general formula (b1).

In formula (b1), at least one of R^(b1) to R^(b3) is an aryl group oralkyl group having a substituent containing a halogen atom, and at leastone of R^(b1) to R^(b3) is an aryl group or an alkyl group having asubstituent containing a sulfonyl group. By virtue of the cation moietyof the component (B1) having both a substituent containing a halogenatom and a substituent containing a sulfonyl group, reactivity of theresist composition and solubility of the resist composition in adeveloping solution is enhanced. By virtue of including the component(B1), according to the resist composition of the present embodiment, itis presumed that lithography properties (reduced roughness) can beimproved, and sensitivity can be enhanced.

(Method of Forming a Resist Pattern)

The method of forming a resist pattern according to the second aspect ofthe present invention includes: using a resist composition according tothe first aspect to form a resist film on a substrate; exposing theresist film; and developing the exposed resist film to form a resistpattern.

The method for forming a resist pattern according to the presentembodiment can be performed, for example, as follows.

Firstly, a resist composition of the first aspect is applied to asubstrate using a spinner or the like, and a bake treatment (postapplied bake (PAB)) is conducted at a temperature of 80 to 150° C. for40 to 120 seconds, preferably 60 to 90 seconds, to form a resist film.

Following selective exposure of the thus formed resist film, either byexposure through a mask having a predetermined pattern formed thereon(mask pattern) using an exposure apparatus such an electron beamlithography apparatus or an EUV exposure apparatus, or by patterning viadirect irradiation with an electron beam without using a mask pattern,baking treatment (post exposure baking (PEB)) is conducted undertemperature conditions of 80 to 150° C. for 40 to 120 seconds, andpreferably 60 to 90 seconds.

Next, the resist film is subjected to a developing treatment. Thedeveloping treatment is conducted using an alkali developing solution inthe case of an alkali developing process, and a developing solutioncontaining an organic solvent (organic developing solution) in the caseof a solvent developing process.

After the developing treatment, it is preferable to conduct a rinsetreatment. The rinse treatment is preferably conducted using pure waterin the case of an alkali developing process, and a rinse solutioncontaining an organic solvent in the case of a solvent developingprocess.

In the case of a solvent developing process, after the developingtreatment or the rinsing, the developing solution or the rinse liquidremaining on the pattern can be removed by a treatment using asupercritical fluid.

After the developing treatment or the rinse treatment, drying isconducted. If desired, bake treatment (post bake) can be conductedfollowing the developing.

In this manner, a resist pattern can be formed.

The substrate is not specifically limited and a conventionally knownsubstrate can be used. For example, substrates for electroniccomponents, and such substrates having wiring patterns formed thereoncan be used. Specific examples of the material of the substrate includemetals such as silicon wafer, copper, chromium, iron and aluminum; andglass. Suitable materials for the wiring pattern include copper,aluminum, nickel, and gold.

Further, as the substrate, any one of the above-mentioned substratesprovided with an inorganic and/or organic film on the surface thereofmay be used. As the inorganic film, an inorganic antireflection film(inorganic BARC) can be used. As the organic film, an organicantireflection film (organic BARC) and an organic film such as alower-layer organic film used in a multilayer resist method can be used.

Here, a “multilayer resist method” is method in which at least one layerof an organic film (lower-layer organic film) and at least one layer ofa resist film (upper resist film) are provided on a substrate, and aresist pattern formed on the upper resist film is used as a mask toconduct patterning of the lower-layer organic film. This method isconsidered as being capable of forming a pattern with a high aspectratio. More specifically, in the multilayer resist method, a desiredthickness can be ensured by the lower-layer organic film, and as aresult, the thickness of the resist film can be reduced, and anextremely fine pattern with a high aspect ratio can be formed.

The multilayer resist method is broadly classified into a method inwhich a double-layer structure consisting of an upper-layer resist filmand a lower-layer organic film is formed (double-layer resist method),and a method in which a multilayer structure having at least threelayers consisting of an upper-layer resist film, a lower-layer organicfilm and at least one intermediate layer (thin metal film or the like)provided between the upper-layer resist film and the lower-layer organicfilm (triple-layer resist method).

The wavelength to be used for exposure is not particularly limited andthe exposure can be conducted using radiation such as ArF excimer laser,KrF excimer laser, F₂ excimer laser, extreme ultraviolet rays (EUV),vacuum ultraviolet rays (VUV), electron beam (EB), X-rays, and softX-rays. The resist composition of the present embodiment is effective toKrF excimer laser, ArF excimer laser, EB and EUV, and more effective toArF excimer laser, EB and EUV, and most effective to EB and EUV. Thatis, the method of forming a resist pattern according to the presentembodiment is effective in the case where the step of exposing theresist film includes exposing the resist film with extreme ultravioletrays (EUV) or electron beam (EB).

The exposure of the resist film can be either a general exposure (dryexposure) conducted in air or an inert gas such as nitrogen, orimmersion exposure (immersion lithography).

In immersion lithography, the region between the resist film and thelens at the lowermost point of the exposure apparatus is pre-filled witha solvent (immersion medium) that has a larger refractive index than therefractive index of air, and the exposure (immersion exposure) isconducted in this state.

The immersion medium preferably exhibits a refractive index larger thanthe refractive index of air but smaller than the refractive index of theresist film to be exposed. The refractive index of the immersion mediumis not particularly limited as long as it satisfies the above-mentionedrequirements.

Examples of this immersion medium which exhibits a refractive index thatis larger than the refractive index of air but smaller than therefractive index of the resist film include water, fluorine-based inertliquids, silicon-based solvents and hydrocarbon-based solvents.

Specific examples of the fluorine-based inert liquids include liquidscontaining a fluorine-based compound such as C₃HCl₂F₅, C₄F₉OCH₃,C₄F₉OC₂H₅ or C₅H₃F₇ as the main component, which have a boiling pointwithin a range from 70 to 180° C. and preferably from 80 to 160° C. Afluorine-based inert liquid having a boiling point within theabove-mentioned range is advantageous in that the removal of theimmersion medium after the exposure can be conducted by a simple method.

As a fluorine-based inert liquid, a perfluoroalkyl compound in which allof the hydrogen atoms of the alkyl group are substituted with fluorineatoms is particularly desirable. Examples of these perfluoroalkylcompounds include perfluoroalkylether compounds and perfluoroalkylaminecompounds.

Specifically, one example of a suitable perfluoroalkylether compound isperfluoro(2-butyl-tetrahydrofuran) (boiling point 102° C.), and anexample of a suitable perfluoroalkylamine compound isperfluorotributylamine (boiling point 174° C.).

As the immersion medium, water is preferable in terms of cost, safety,environment and versatility.

As an example of the alkali developing solution used in an alkalideveloping process, a 0.1 to 10% by weight aqueous solution oftetramethylammonium hydroxide (TMAH) can be given.

As the organic solvent contained in the organic developing solution usedin a solvent developing process, any of the conventional organicsolvents can be used which are capable of dissolving the component (A)(prior to exposure). Specific examples of the organic solvent includepolar solvents such as ketone solvents, ester solvents, alcoholsolvents, nitrile solvents, amide solvents and ether solvents, andhydrocarbon solvents.

A ketone solvent is an organic solvent containing C—C(═O)—C within thestructure thereof. An ester solvent is an organic solvent containingC—C(═O)—O—C within the structure thereof. An alcohol solvent is anorganic solvent containing an alcoholic hydroxy group in the structurethereof. An “alcoholic hydroxy group” refers to a hydroxy group bondedto a carbon atom of an aliphatic hydrocarbon group. A nitrile solvent isan organic solvent containing a nitrile group in the structure thereof.An amide solvent is an organic solvent containing an amide group withinthe structure thereof. An ether solvent is an organic solvent containingC—O—C within the structure thereof.

Some organic solvents have a plurality of the functional groups whichcharacterizes the aforementioned solvents within the structure thereof.In such a case, the organic solvent can be classified as any type of thesolvent having the characteristic functional group. For example,diethyleneglycol monomethylether can be classified as either an alcoholsolvent or an ether solvent.

A hydrocarbon solvent consists of a hydrocarbon which may behalogenated, and does not have any substituent other than a halogenatom. Examples of the halogen atom include a fluorine atom, a chlorineatom, a bromine atom and an iodine atom, and a fluorine atom ispreferable.

As the organic solvent contained in the organic developing solution,among these, a polar solvent is preferable, and ketone solvents, estersolvents and nitrile solvents are preferable.

Examples of ketone solvents include 1-octanone, 2-octanone, 1-nonanone,2-nonanone, acetone, 4-heptanone, 1-hexanone, 2-hexanone, diisobutylketone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethylketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone,diacetonylalcohol, acetylcarbinol, acetophenone, methyl naphthyl ketone,isophorone, propylenecarbonate, γ-butyrolactone and methyl amyl ketone(2-heptanone). Among these examples, as a ketone solvent, methyl amylketone (2-heptanone) is preferable.

Examples of ester solvents include methyl acetate, butyl acetate, ethylacetate, isopropyl acetate, amyl acetate, isoamyl acetate, ethylmethoxyacetate, ethyl ethoxyacetate, propylene glycol monomethyl etheracetate, ethylene glycol monoethyl ether acetate, ethylene glycolmonopropyl ether acetate, ethylene glycol monobutyl ether acetate,ethylene glycol monophenyl ether acetate, diethylene glycol monomethylether acetate, diethylene glycol monopropyl ether acetate, diethyleneglycol monoethyl ether acetate, diethylene glycol monophenyl etheracetate, diethylene glycol monobutyl ether acetate, diethylene glycolmonoethyl ether acetate, 2-methoxybutyl acetate, 3-methoxybutyl acetate,4-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate,3-ethyl-3-methoxybutyl acetate, propylene glycol monomethyl etheracetate, propylene glycol monoethyl ether acetate, propylene glycolmonopropyl ether acetate, 2-ethoxybutyl acetate, 4-ethoxybutyl acetate,4-propoxybutyl acetate, 2-methoxypentyl acetate, 3-methoxypentylacetate, 4-methoxypentyl acetate, 2-methyl-3-methoxypentyl acetate,3-methyl-3-methoxypentyl acetate, 3-methyl-4-methoxypentyl acetate,4-methyl-4-methoxypentyl acetate, propylene glycol diacetate, methylformate, ethyl formate, butyl formate, propyl formate, ethyl lactate,butyl lactate, propyl lactate, ethyl carbonate, propyl carbonate, butylcarbonate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, butylpyruvate, methyl acetoacetate, ethyl acetoacetate, methyl propionate,ethyl propionate, propyl propionate, isopropyl propionate, methyl2-hydroxypropionate, ethyl 2-hydroxypropionate,methyl-3-methoxypropionate, ethyl-3-methoxypropionate,ethyl-3-ethoxypropionate and propyl-3-methoxypropionate. Among theseexamples, as an ester solvent, butyl acetate is preferable.

Examples of nitrile solvents include acetonitrile, propionitrile,valeronitrile, and butyronitrile.

If desired, the organic developing solution may have a conventionaladditive blended. Examples of the additive include surfactants. Thesurfactant is not particularly limited, and for example, an ionic ornon-ionic fluorine and/or silicon surfactant can be used.

As the surfactant, a non-ionic surfactant is preferable, and a non-ionicfluorine surfactant or a non-ionic silicon surfactant is morepreferable.

When a surfactant is added, the amount thereof based on the total amountof the organic developing solution is generally 0.001 to 5% by weight,preferably 0.005 to 2% by weight, and more preferably 0.01 to 0.5% byweight.

The developing treatment can be performed by a conventional developingmethod. Examples thereof include a method in which the substrate isimmersed in the developing solution for a predetermined time (a dipmethod), a method in which the developing solution is cast up on thesurface of the substrate by surface tension and maintained for apredetermined period (a puddle method), a method in which the developingsolution is sprayed onto the surface of the substrate (spray method),and a method in which the developing solution is continuously ejectedfrom a developing solution ejecting nozzle while scanning at a constantrate to apply the developing solution to the substrate while rotatingthe substrate at a constant rate (dynamic dispense method).

As the organic solvent contained in the rinse liquid used in the rinsetreatment after the developing treatment in the case of a solventdeveloping process, any of the aforementioned organic solvents containedin the organic developing solution can be used which hardly dissolvesthe resist pattern. In general, at least one solvent selected from thegroup consisting of hydrocarbon solvents, ketone solvents, estersolvents, alcohol solvents, amide solvents and ether solvents is used.Among these, at least one solvent selected from the group consisting ofhydrocarbon solvents, ketone solvents, ester solvents, alcohol solventsand amide solvents is preferable, more preferably at least one solventselected from the group consisting of alcohol solvents and estersolvents, and an alcohol solvent is particularly desirable.

The alcohol solvent used for the rinse liquid is preferably a monohydricalcohol of 6 to 8 carbon atoms, and the monohydric alcohol may belinear, branched or cyclic. Specific examples thereof include 1-hexanol,1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol,3-heptanol, 3-octanol, 4-octanol and benzyl alcohol. Among these,1-hexanol, 2-heptanol and 2-hexanol are preferable, and 1-hexanol and2-hexanol are more preferable.

As the organic solvent, one kind of solvent may be used alone, or two ormore kinds of solvents may be used in combination. Further, an organicsolvent other than the aforementioned examples or water may be mixedtogether. However, in consideration of the development characteristics,the amount of water within the rinse liquid, based on the total amountof the rinse liquid is preferably 30% by weight or less, more preferably10% by weight or less, still more preferably 5% by weight or less, andmost preferably 3% by weight or less.

If desired, the rinse solution may have a conventional additive blended.Examples of the additive include surfactants. Examples of the additiveinclude surfactants. As the surfactant, the same surfactants as thosedescribed above can be mentioned, a non-ionic surfactant is preferable,and a non-ionic fluorine surfactant or a non-ionic silicon surfactant ismore preferable.

When a surfactant is added, the amount thereof based on the total amountof the rinse liquid is generally 0.001 to 5% by weight, preferably 0.005to 2% by weight, and more preferably 0.01 to 0.5% by weight.

The rinse treatment using a rinse liquid (washing treatment) can beconducted by a conventional rinse method. Examples of the rinse methodinclude a method in which the rinse liquid is continuously applied tothe substrate while rotating it at a constant rate (rotational coatingmethod), a method in which the substrate is immersed in the rinse liquidfor a predetermined time (dip method), and a method in which the rinseliquid is sprayed onto the surface of the substrate (spray method).

In the method of forming a resist pattern according to the presentembodiment, by virtue of using the resist composition of the firstaspect, it becomes possible to enhance sensitivity in the formation of aresist pattern, and a resist pattern having improved lithographyproperties (such as reduced roughness) can be formed.

(Compound)

The compound according to a third aspect of the present invention isrepresented by general formula (b1) shown below.

In the formula, R^(b1) represents an aryl group which may have asubstituent; R^(b2) and R^(b3) each independently represents an arylgroup which may have a substituent or an alkyl group which may have asubstituent;

R^(b2) and R^(b3) may be mutually bonded to form a ring with the sulfuratom; provided that at least one of the aryl group represented by R^(b1)and the aryl group or the alkyl group represented by R^(b2) or R^(b3)has a substituent containing a halogen atom, and at least one of thearyl group represented by R^(b1) and the aryl group or the alkyl grouprepresented by R^(b2) or R^(b3) has a substituent containing a sulfonylgroup; and X⁻ represents a counteranion.

The compound represented by general formula (b1) above is the same asthe component (B1) described above for the resist composition of thepresent embodiment.

(Acid Generator)

The acid generator according to the fourth aspect of the presentinvention includes the compound of the third aspect.

The acid generator is useful as an acid-generator component for achemically amplified resist composition. By virtue of using suchacid-generator component in a chemically amplified resist composition,it becomes possible to enhance sensitivity in the formation of a resistpattern, and a resist pattern having improved lithography properties(such as reduced roughness) can be formed. In particular, by virtue ofusing such acid-generator component, high sensitivity to an EB or EUVexposure source can be obtained. In addition, according to a chemicallyamplified resist composition containing such acid-generator component,resolution performance is improved.

(Compound (Intermediate))

The compound according to a fifth aspect of the present invention isrepresented by general formula (bp-1).

The compound according to the fifth aspect is useful as an intermediatein producing a compound according to the third aspect.

In the formula, R^(p1) represents an aryl group which may have asubstituent; R^(p2) and R^(p3) each independently represents an arylgroup which may have a substituent or an alkyl group which may have asubstituent;

R^(p2) and R^(p3) may be mutually bonded to form a ring with the sulfuratom; provided that at least one of the aryl group represented by R^(p1)to R^(p3) is the aforementioned aryl group or alkyl group having asubstituent containing a halogen atom, and at least one of R^(p1) toR^(p3) is an aryl group or alkyl group having a group represented by theformula: —SR^(p4); R^(p4) represents an alkyl group; and Xp⁻ representsa counteranion.

In formula (bp-1), the aryl group (which may have a substituent)represented by R^(p1) is the same as defined for the aryl group (whichmay have a substituent) represented by R^(b1).

In formula (bp-1), the aryl group or alkyl group (which may have asubstituent) represented by R^(p2) or R^(p3) is the same as defined forthe aryl group or alkyl group (which may have a substituent) representedby R^(b2) or R^(b3) in the aforementioned formula (b1).

In formula (bp-1), at least one of R^(p1) to R^(p3) is theaforementioned aryl group or alkyl group having a substituent containinga halogen atom, and at least one of R^(p1) to R^(p3) is an aryl group oralkyl group having a group represented by the formula: —SR^(p4). R^(p4)represents an alkyl group.

Regarding R^(p1) to R^(p3), the substituent containing a halogen atom isthe same as defined for the substituent containing a halogen atomdescribed above in relation to R^(b1) to R^(b3) in the aforementionedformula (b1).

In the group represented by the formula: —SR^(p4), the alkyl group forR^(p4) is preferably a linear or branched alkyl group. Examples of thelinear or branched alkyl group include a methyl group, an ethyl group, apropyl group, an isopropyl group, an n-butyl group, an isobutyl group, atert-butyl group, a pentyl group, an isopentyl group and a neopentylgroup, preferably a methyl group or an ethyl group, and more preferablya methyl group.

Further, regarding the group represented by the formula —SR^(p4), in thecase where R^(p2) and R^(p3) are mutually bonded to form a ring with thesulfur atom, and the ring is formed together with the group representedby the formula —SR^(p4), the group represented by the formula —SR^(p4)may be present in the ring in the form of a divalent group in which onehydrogen atom has been removed from the alkyl group R^(p4), or adivalent group “—S—” (i.e., —SR^(p4′)—(R^(p4′) represents an alkylenegroup or a single bond).

In formula (bp-1), examples of the counteranion represented by Xp⁻include a halogen anion (Cl⁻, Br⁻, I⁻), a carboxylic acid anion (such asan acetic acid anion) and RpSO₃ ⁻. Rp is an alkyl group having 1 to 5carbon atoms (a methyl group, an ethyl group, a propyl group, anisopropyl group, an n-butyl group, an isobutyl group, a tert-butylgroup, a pentyl group, an isopentyl group or a neopentyl group) or afluorinated alkyl group having 1 to 5 carbon atoms, and is preferably atrifluoromethyl group.

(Production Method of Compound)

The method of producing a compound according to a sixth aspect of thepresent invention includes oxidizing a compound represented by generalformula (bp-1) shown below (hereafter, referred to as “compound (bp-1)”)to obtain a compound represented by general formula (b1-1) shown below(hereafter, referred to as “compound (b1-1)”).

In the formula, R^(p1) represents an aryl group which may have asubstituent; R^(p2) and R^(p3) each independently represents an arylgroup which may have a substituent or an alkyl group which may have asubstituent;

R^(p2) and R^(p3) may be mutually bonded to form a ring with the sulfuratom; provided that at least one of the aryl group represented by R^(p1)and the aryl group or the alkyl group represented by R^(p2) or R^(p3)has a substituent containing a halogen atom, and at least one of thearyl group represented by R^(p1) and the aryl group or the alkyl grouprepresented by R^(p2) or R^(p3) has a group represented by the formula:—SR^(p4); R^(p4) represents an alkyl group; and Xp⁻ represents acounteranion.

In the formula, R^(b11) represents an aryl group which may have asubstituent; R^(b12) and R^(b13) each independently represents an arylgroup which may have a substituent or an alkyl group which may have asubstituent; R^(b12) and R^(b13) may be mutually bonded to form a ringwith the sulfur atom; provided that at least one of the aryl grouprepresented by R^(b11) and the aryl group or the alkyl group representedby R^(b12) or R^(b13) has a substituent containing a halogen atom, andat least one of the aryl group represented by R^(b11) and the aryl groupor the alkyl group represented by R^(b12) or R^(b13) has a grouprepresented by the formula: —SO₂—R^(p4); R^(p4) represents an alkylgroup; and Xp⁻ represents a counteranion.

The compound (bp-1) is the same as defined for the compound according tothe fifth aspect described above.

In formula (b1-1), the aryl group (which may have a substituent)represented by R^(b11) is the same as defined for the aryl group (whichmay have a substituent) represented by R^(b1) in the aforementionedformula (b1).

In formula (b1-1), the aryl group or alkyl group (which may have asubstituent) represented by R^(b12) or R^(b13) is the same as definedfor the aryl group or alkyl group (which may have a substituent)represented by R^(b2) or R^(b3) in the aforementioned formula (b1).

In formula (b1-1), at least one of the aryl group represented by R^(b1)and the aryl group or the alkyl group represented by R^(b12) or R^(b13)has a substituent containing a halogen atom, and at least one of thearyl group represented by R^(b11) and the aryl group or the alkyl grouprepresented by R^(b12) or R^(b13) has a group represented by theformula: —SO₂—R^(p4).

Regarding R^(b11) to R^(b13), the substituent containing a halogen atomis the same as defined for the substituent containing a halogen atomdescribed above in relation to R^(b1) to R^(b3) in the aforementionedformula (b1).

In the group represented by the formula —SO₂—R^(p4), the alkyl grouprepresented by R^(p4) is the same as defined for the alkyl grouprepresented by R^(p4) in the “group represented by the formula:—SR^(p4)” described above in relation to R^(p1) to R^(p3) in theaforementioned formula (bp-1).

In formula (b1-1), the counteranion represented by Xp⁻ is the same asdefined for the counteranion represented by Xp⁻ in the aforementionedformula (bp-1).

The method of oxidizing the compound (bp-1) is not particularly limited,and examples thereof include an oxidation reaction (e.g., oxoneoxidation) in which the compound (bp-1) is reacted with potassiumperoxymonosulfate (2KHSO₅. KHSO₄. K₂SO₄).

The solvent used in the oxidation reaction is not particularly limited,and examples thereof include at least one member selected from the groupconsisting of water and an alcohol solvent such as methanol, ethanol orisopropanol.

The reaction temperature in the oxidation reaction is not particularlylimited, and is preferably 0 to 50° C., more preferably 5 to 40° C.

The reaction time in the oxidation reaction is not particularly limited,and is preferably 1 to 72 hours, more preferably 2 to 60 hours.

As the compound (bp-1), commercially available compound may be used, orthe compound may be synthesized by a conventional method.

The compound (b1-1) may be subjected to a salt exchange reaction with anammonium salt having a desired anion, so as to obtain a compound havingthe desired anion (acid generator (B1)).

After the salt exchange reaction, the compound in the reaction liquidmay be separated and purified. The separation and purification can beconducted by a conventional method. For example, any of concentration,solvent extraction, distillation, crystallization, re-crystallizationand chromatography may be used.

The structure of the compound obtained in the manner described above canbe identified by a general organic analysis method such as ¹H-nuclearmagnetic resonance (NMR) spectrometry, ¹³C-NMR spectrometry, ¹⁹F-NMRspectrometry, infrared absorption (IR) spectrometry, mass spectrometry(MS), elementary analysis and X-ray diffraction analysis.

EXAMPLES

As follows is a description of examples of the present invention,although the scope of the present invention is by no way limited bythese examples.

In the following examples, a compound represented by a chemical formula(1) is denoted as “compound (1)”, and the same applies for compoundsrepresented by other chemical formulae.

<Production of Compound>

Production Example 1

Diphenylsulfoxide (20 g, 99 mmol) and trimethylsilyltrifluoromethanesulfonate (44 g, 198 mmol) were dissolved in THF (64 g), and a THFsolution of 3-trifluoromethyl-4-fluorophenylmagnesiumbromide wasdropwise added thereto while maintaining the reaction system at atemperature not exceeding −5° C. The THF solution of3-trifluoromethyl-4-fluorophenylmagnesiumbromide was prepared from5-bromo-2-fluorobenzotrifluoride (24 g, 99 mmol), magnesium (2.4 g, 99mmol) and THF (93 g) by a conventional method. After the dropwiseaddition, the reaction was continued for 1 hour to complete thereaction. The reaction liquid was added to ultrapure water (370 g) over1 hour, and dichloromethane (490 g) was added thereto, followed bystirring for 30 minutes and removing the aqueous phase. The organicphase was washed with ultrapure water (370 g) 3 times, and the organicphase was dropwise added to methyl tert-butyl ether (MTBE) (4,900 g),followed by subjecting the precipitated solid to filtration. The residuewas dried under reduced pressure, so as to obtain intermediate B1 (20.8g, yield=43.0%).

Intermediate B1 (20 g, 41 mmol) was dissolved in acetonitrile (100 g),and a 15 wt % aqueous solution of methyl mercaptan sodium (21 g, 45mmol) was dropwise added while maintaining the reaction system at atemperature not exceeding −10° C. After the dropwise addition, thereaction was continued at −10° C. for 1 hour to complete the reaction.Then, the aqueous phase was removed, and the organic phase wasconcentrated using a rotary evaporator. The concentrate was dissolved indichloromethane (190 g). The resultant was washed with 1% hydrochloricacid (65 g), followed by washing with ultrapure water (65 g) 3 times.Then, the organic phase was dropwise added to MTBE (1,900 g), and theprecipitated solid was subjected to filtration. The residue was driedunder reduced pressure, so as to obtain intermediate B2 (819.6 g,yield=90.9%).

Intermediate B2 (19 g, 36 mmol) was dissolved in a mixed solution ofultrapure water (14 g) and methanol (43 g), and Oxone (registeredtrademark) (33 g, 54 mmol, molecular formula: 2KHSO₅.KHSO₄K₂SO₄,molecular weight: 614.76) was added thereto, followed by stirring atroom temperature for 48 hours. The reaction liquid was subjected tofiltration, and ultrapure water (29 g) and dichloromethane (180 g) wereadded thereto, followed by stirring for 30 minutes and removing theaqueous phase. The resultant was washed with a saturated aqueoussolution of sodium hydrogen sulfite (60 g), followed by washing withultrapure water (60 g) 3 times. The organic phase was dropwise added toMTBE (1,800 g), and the precipitated solid was subjected to filtration.The residue was dried under reduced pressure, so as to obtain precursorB1 (14.1 g, yield=70.0%).

Precursor B1 (12 g, 21 mmol) and compound 1 (12.7 g, 24 mmol) weredissolved in dichloromethane (100 g), and ultrapure water (30 g) wasadded thereto, followed by conducting a reaction at room temperature for30 minutes. After the reaction, the aqueous phase was removed, and theorganic phase was washed with ultrapure water (30 g) 4 times. Theorganic phase was concentrated and solidified using a rotary evaporator,so as to obtain acid generator (B1-1) (15.6 g, yield=91.2%).

Production Example 2

Thianthrene-5-oxide (17 g, 73 mmol) andtrimethylsilyltrifluoromethanesulfonate (32.5 g, 146 mmol) weredissolved in THF (50 g), and a THF solution of3-trifluoromethylphenylmagnesiumbromide was dropwise added thereto whilemaintaining the reaction system at a temperature not exceeding −5° C.The THF solution of trifluoromethylphenylmagnesiumbromide was preparedfrom 3-bromo-benzotrifluoride (16.5 g, 73 mmol), magnesium (1.8 g, 73mmol) and THF (64 g) by a conventional method. After the dropwiseaddition, the reaction was continued for 1 hour to complete thereaction. The reaction liquid was added to ultrapure water (270 g) over1 hour. Then, dichloromethane (360 g) was added, followed by stirringfor 30 minutes and removing the aqueous phase. The organic phase waswashed with ultrapure water (270 g) 3 times, and the organic phase wasdropwise added to MTBE (3,600 g), followed by subjecting theprecipitated solid to filtration. The residue was dried under reducedpressure, so as to obtain intermediate B3 (17.7 g, yield=47.5%).

Intermediate B3 (16 g, 31 mmol) was dissolved in a mixed solution ofultrapure water (12 g) and methanol (36 g), and oxone (29 g, 47 mmol)was added thereto, followed by stirring at room temperature for 48hours. The reaction liquid was subjected to filtration, and ultrapurewater (24 g) and dichloromethane (150 g) were added thereto, followed bystirring for 30 minutes and removing the aqueous phase. The resultantwas washed with a saturated aqueous solution of sodium hydrogen sulfite(50 g), followed by washing with ultrapure water (50 g) 3 times. Theorganic phase was dropwise added to MTBE (1,500 g), and the precipitatedsolid was subjected to filtration. The residue was dried under reducedpressure, so as to obtain precursor B2 (12.5 g, yield=73.3%).

Precursor B2 (12 g, 22 mmol) and compound 1 (13 g, 24 mmol) weredissolved in dichloromethane (100 g), and ultrapure water (30 g) wasadded thereto, followed by conducting a reaction at room temperature for30 minutes.

After the reaction, the aqueous phase was removed, and the organic phasewas washed with ultrapure water (30 g) 4 times. The organic phase wasconcentrated and solidified using a rotary evaporator, so as to obtainacid generator (B1-2) (15.9 g, yield=92.4%).

Production Example 3

Benzothiophene-1-oxide (18 g, 120 mmol) andtrimethylsilyltrifloromethanesulfonate (53.3 g, 240 mmol) were dissolvedin THF (71 g), and a THF solution of3-trifluoromethyl-4-fluorophenylmagnesiumbromide was dropwise addedthereto while maintaining the reaction system at a temperature notexceeding −5° C. The THF solution of3-trifluoromethyl-4-fluorophenylmagnesiumbromide was prepared from5-bromo-2-fluorobenzotrifluoride (29.1 g, 120 mmol), magnesium (1.8 g,120 mmol) and THF (112 g) by a conventional method. After the dropwiseaddition, the reaction was continued for 1 hour to complete thereaction. The reaction liquid was added to ultrapure water (430 g) over1 hour. Then, dichloromethane (570 g) was added, followed by stirringfor 30 minutes and removing the aqueous phase. The organic phase waswashed with ultrapure water (430 g) 3 times, and the organic phase wasdropwise added to MTBE (5,700 g), followed by subjecting theprecipitated solid to filtration. The residue was dried under reducedpressure, so as to obtain intermediate B4 (21.9 g, yield=41.0%).

Intermediate B4 (20 g, 45 mmol) was dissolved in acetonitrile (100 g),and a 15 wt % aqueous solution of methyl mercaptan sodium (23.0 g, 49mmol) was dropwise added while maintaining the reaction system at atemperature not exceeding −10° C. After the dropwise addition, thereaction was continued at −10° C. for 1 hour to complete the reaction.Then, the aqueous phase was removed, and the organic phase wasconcentrated using a rotary evaporator. The concentrate was dissolved indichloromethane. The resultant was washed with 1% hydrochloric acid (60g), followed by washing with ultrapure water (60 g) 3 times. Then, theorganic phase was dropwise added to MTBE (1,900 g), and the precipitatedsolid was subjected to filtration. The residue was dried under reducedpressure, so as to obtain intermediate B5 (19.0 g, yield=89.5%).

Intermediate B5 (19 g, 40 mmol) was dissolved in a mixed solution ofultrapure water (14 g) and methanol (43 g), and oxone (37 g, 60 mmol)was added thereto, followed by stirring at room temperature for 48hours. The reaction liquid was subjected to filtration, and ultrapurewater (30 g) and dichloromethane (180 g) were added thereto, followed bystirring for 30 minutes and removing the aqueous phase. The resultantwas washed with a saturated aqueous solution of sodium hydrogen sulfite(70 g), followed by washing with ultrapure water (60 g) 3 times. Theorganic phase was dropwise added to MTBE (1,800 g), and the precipitatedsolid was subjected to filtration. The residue was dried under reducedpressure, so as to obtain precursor B3 (14.6 g, yield=72.1%).

Precursor B3 (12 g, 24 mmol) and compound 2 (12.8 g, 26 mmol) weredissolved in dichloromethane (100 g), and ultrapure water (30 g) wasadded thereto, followed by conducting a reaction at room temperature for30 minutes. After the reaction, the aqueous phase was removed, and theorganic phase was washed with ultrapure water (30 g) 4 times. Theorganic phase was concentrated and solidified using a rotary evaporator,so as to obtain acid generator (B1-3) (14.9 g, yield=90.5%).

Production Example 4

3-bromothioanisole (30 g, 148 mmol), magnesium (3.6 g, 148 mmol) and THF(150 g) were used to prepare a THF solution of3-methylthiophenylmagnesiumbromide by a conventional method. The THFsolution of 3-methylthiophenylmagnesiumbromide was dropwise added to asolution obtained by diluting thionyl chloride (8.8 g, 74 mmol) in THF(20 g), while maintaining the reaction system at a temperature notexceeding −5° C. After the dropwise addition, the reaction was continuedat room temperature for 1 hour to complete the reaction.

The reaction liquid was added to ultrapure water (150 g) over 1 hour.Then, dichloromethane (210 g) was added, followed by stirring for 30minutes and removing the aqueous phase. The organic phase was washedwith ultrapure water (150 g) 3 times, and the organic phase wasconcentrated using a rotary evaporator. The concentrate wasrecrystallized in cyclohexane, so as to obtain intermediate B6 (10.9 g,yield=50.0%).

Intermediate 6 (10 g, 34 mmol) andtrimethylsilyltrifluoromethanesulfonate (15.1 g, 68 mmol) were dissolvedin THF (25 g), and a THF solution of3,5-bistrifluoromethylbromobenzenemagnesiumbromide was dropwise addedthereto while maintaining the reaction system at a temperature notexceeding −5° C. The THF solution of3,5-bistrifluoromethylbromobenzenemagnesiumbromide was prepared from3,5-bistrifluoromethylbromobenzene (10.0 g, 34 mmol), magnesium (0.8 g,34 mmol) and THF (38 g). After the dropwise addition, the reaction wascontinued for 1 hour to complete the reaction. The reaction liquid wasadded to ultrapure water (150 g) over 1 hour. Then, dichloromethane (200g) was added, followed by stirring for 30 minutes and removing theaqueous phase. The organic phase was washed with ultrapure water (150 g)3 times, and the organic phase was dropwise added to MTBE (2,000 g),followed by subjecting the precipitated solid to filtration. The residuewas dried under reduced pressure, so as to obtain intermediate B7 (14.2g, yield=65.3%).

Intermediate B7 (13 g, 20 mmol) was dissolved in a mixed solution ofultrapure water (20 g) and methanol (60 g), and oxone (31 g, 51 mmol)was added thereto, followed by stirring at room temperature for 48hours. The reaction liquid was subjected to filtration, and ultrapurewater (40 g) and dichloromethane (130 g) were added thereto, followed bystirring for 30 minutes and removing the aqueous phase. The resultantwas washed with a saturated aqueous solution of sodium hydrogen sulfite(60 g), followed by washing with ultrapure water (40 g) 3 times. Theorganic phase was dropwise added to MTBE (1,300 g), and the precipitatedsolid was subjected to filtration. The residue was dried under reducedpressure, so as to obtain precursor B4 (9.2 g, yield=64.1%).

Intermediate B4 (9.0 g, 13 mmol) and compound 3 (5.2 g, 14 mmol) weredissolved in dichloromethane (70 g), and ultrapure water (20 g) wasadded thereto, followed by conducting a reaction at room temperature for30 minutes. After the reaction, the aqueous phase was removed, and theorganic phase was washed with ultrapure water (20 g) 4 times. Theorganic phase was concentrated and solidified using a rotary evaporator,so as to obtain acid generator (B1-4) (10.8 g, yield=93.4%).

Production Example 5

1-Bromo-3,4,5-trifluorobenzene (30 g, 142 mmol), magnesium (3.5 g, 142mmol) and THF (130 g) were used to prepare a THF solution of3,4,5-trifluorophenylmagnesiumbromide. The THF solution of3,4,5-trifluorophenylmagnesiumbromide was dropwise added to a solutionobtained by diluting thionyl chloride (8.5 g, 71 mmol) in THF (17 g),while maintaining the reaction system at a temperature not exceeding −5°C. After the dropwise addition, the reaction was continued for 1 hour tocomplete the reaction.

The reaction liquid was added to ultrapure water (110 g) over 1 hour.Then, dichloromethane (440 g) was added, followed by stirring for 30minutes and removing the aqueous phase. The organic phase was washedwith ultrapure water (110 g) 3 times, and the organic phase wasconcentrated using a rotary evaporator. The concentrate wasrecrystallized in cyclohexane, so as to obtain intermediate B8 (13.2 g,yield=60.0%).

Intermediate B8 (12 g, 39 mmol) was dissolved in benzene (60 g), andtrimethylsilyltrifluoromethanesulfonate (21.5 g, 97 mmol) was dropwiseadded thereto at room temperature.

After the dropwise addition, the reaction was continued at roomtemperature for 2 hours to complete the reaction. The liquid wasseparated into oil and benzene phase. After removing the benzene phase,the oil was dissolved in dichloromethane (180 g), followed by washingwith ultrapure water (60 g) 6 times. The organic phase was concentratedand solidified using a rotary evaporator, so as to obtain intermediateB9 (17.6 g, yield=87.2%).

Intermediate B9 (16 g, 31 mmol) was dissolved in acetonitrile (80 g),and a 15 wt % aqueous solution of methyl mercaptan sodium (31.6 g, 68mmol) was dropwise added while maintaining the reaction system at atemperature not exceeding −10° C. After the dropwise addition, thereaction was continued at −10° C. for 1 hour to complete the reaction.Then, the aqueous phase was removed, and the organic phase wasconcentrated using a rotary evaporator. The obtained concentrate wasdissolved in dichloromethane (160 g). The resultant was washed with 1%hydrochloric acid (50 g), followed by washing with ultrapure water (50g) 3 times. The organic phase was dropwise added to MTBE (1,600 g), andthe precipitated solid was subjected to filtration. The residue wasdried under reduced pressure, so as to obtain intermediate B10 (16.5 g,yield=92.9%).

Intermediate B10 (15 g, 26 mmol) was dissolved in a mixed solution ofultrapure water (23 g) and methanol (68 g), and oxone (40 g, 65 mmol)was added thereto, followed by stirring at room temperature for 48hours. The reaction liquid was subjected to filtration, and ultrapurewater (45 g) and dichloromethane (150 g) were added thereto, followed bystirring for 30 minutes and removing the aqueous phase. The resultantwas washed with a saturated aqueous solution of sodium hydrogen sulfite(75 g), followed by washing with ultrapure water (50 g) 3 times. Theorganic phase was dropwise added to MTBE (1,500 g), and the precipitatedsolid was subjected to filtration. The residue was dried under reducedpressure, so as to obtain precursor B5 (9.1 g, yield=54.4%).

Intermediate B5 (8.0 g, 12 mmol) and compound 4 (5.8 g, 14 mmol) weredissolved in dichloromethane (60 g), and ultrapure water (20 g) wasadded thereto, followed by conducting a reaction at room temperature for30 minutes. After the reaction, the aqueous phase was removed, and theorganic phase was washed with ultrapure water (20 g) 4 times. Theorganic phase was concentrated and solidified using a rotary evaporator,so as to obtain acid generator (B1-5) (9.6 g, yield=94.1%).

Each of the obtained compounds was analyzed by NMR, and the structurethereof was identified by the following analysis results.

Compound (B1-1)

¹H-NMR (DMSO, 400 MHz): δ (ppm)=8.41 (s, Ph, 1H), 8.12 (d, Ph, 1H),7.74-8.00 (m, Ph, 11H), 4.86-5.01 (m, CF2CH2, 1H), 4.55 (s, HO, 1H),4.04-4.26 (m, CH2, 2H), 3.52 (s, CH3, 3H), 2.27-2.48 (m, CFCH, 1H),2.10-2.18 (m, Adamantyl, 2H), 1.89-2.04 (m, CFCH, 1H1), 1.46-1.73 (m,Adamantyl, 12H)

¹⁹F-NMR (DMSO, 376 MHz): δ(ppm)=−61.8 ppm, −112.5, −121.2, −203.2

Compound (B1-2)

¹H-NMR (DMSO, 400 MHz): δ(ppm)=8.75 (s, ArH, 1H), 8.49 (t, ArH, 2H),8.32 (d, ArH, 1H), 8.00-8.22 (m, ArH, 5H), 7.88 (d, ArH, 2H), 7.50 (d,ArH, 1H), 4.86-5.01 (m, CF2CH2, 1H), 4.55 (s, HO, 1H), 4.04-4.26 (m,CH2, 2H), 2.27-2.48 (m, CFCH, 1H), 2.10-2.18 (m, Adamantyl, 2H),1.89-2.04 (m, CFCH, 1H), 1.46-1.73 (m, Adamantyl, 12H)

¹⁹F-NMR (DMSO, 376 MHz): δ(ppm)=−62.3 ppm, −112.5, −121.2, −203.2

Compound (B1-3)

¹H-NMR (DMSO, 400 MHz): δ(ppm)=8.38 (s, 1H, ArH), 8.27 (d, 2H, ArH),8.11-8.15 (m, 2H, ArH), 7.67-7.84 (m, 4H, ArH), 4.55 (m, CF2CH2, HO,4H), 3.56 (s, CH3, 3H), 1.46-2.18 (m, Adamantyl, 14H)

¹⁹F-NMR (DMSO, 376 MHz): δ(ppm)=−62.1 ppm, −114.5

Compound (B1-4) ¹H-NMR (DMSO, 400 MHz): δ (ppm)=8.60-8.80 (m, ArH, 5H),8.41 (d, ArH, 2H), 8.28 (d, ArH, 2H), 8.06 (t, ArH, 2H), 4.78 (m, CH,1H), 4.66 (t, CH, 1H), 3.88 (t, CH, 1H), 3.31-3.36 (m, CH, 1H),2.47-2.49 (m, CH, 1H), 1.73-2.21 (m, CH2, 4H) ¹⁹F-NMR (DMSO, 376 MHz): δ(ppm)=−61.2, −107.7

Compound (B1-5)

¹H-NMR (DMSO, 400 MHz): δ (ppm)=7.98-8.07 (m, ArH, 6H), 7.94 (t, ArH,1H), 7.83 (t, ArH, 2H), 4.55 (t, CF2CH2, 2H), 3.53 (s, CH3, 6H),1.64-1.96 (m, Adamantyl, 15H)

¹⁹F-NMR (DMSO, 376 MHz): δ(ppm)=−102.3, −111.2

<Production of Resist Composition>

Examples 1 to 10, Comparative Examples 1 to 10

The components shown in Tables 1 and 2 were mixed together and dissolvedto obtain each resist composition.

TABLE 1 Component Component Component Component (A) (B) (D) (S)Comparative (A)-1 (B2)-1 (D)-1 (S)-1 Example 1 [100] [20.9] [3.8] [6400]Comparative (A)-1 (B2)-2 (D)-1 (S)-1 Example 2 [100] [20.7] [3.8] [6400]Example 1 (A)-1 (B1)-1 (D)-1 (S)-1 [100] [22.6] [3.8] [6400] Example 2(A)-1 (B1)-2 (D)-1 (S)-1 [100] [22.2] [3.8] [6400] Comparative (A)-1(B2)-3 (D)-1 (S)-1 Example 3 [100] [18.1] [3.8] [6400] Example 3 (A)-1(B1)-3 (D)-1 (S)-1 [100] [19.9] [3.8] [6400] Comparative (A)-1 (B2)-4(D)-1 (S)-1 Example 4 [100] [21.3] [3.8] [6400] Example 4 (A)-1 (B1)-4(D)-1 (S)-1 [100] [25.7] [3.8] [6400] Comparative (A)-1 (B2)-5 (D)-1(S)-1 Example 5 [100] [19.8] [3.8] [6400] Example 5 (A)-1 (B1)-5 (D)-1(S)-1 [100] [23.2] [3.8] [6400]

TABLE 2 Component Component Component Component (A) (B) (D) (S)Comparative (A)-2 (B2)-1 (D)-1 (S)-1 Example 6 [100] [20.9] [3.8] [6400]Comparative (A)-2 (B2)-2 (D)-1 (S)-1 Example 7 [100] [20.7] [3.8] [6400]Example 6 (A)-2 (B1)-1 (D)-1 (S)-1 [100] [22.6] [3.8] [6400] Example 7(A)-2 (B1)-2 (D)-1 (S)-1 [100] [22.2] [3.8] [6400] Comparative (A)-2(B2)-3 (D)-1 (S)-1 Example 8 [100] [18.1] [3.8] [6400] Example 8 (A)-2(B1)-3 (D)-1 (S)-1 [100] [19.9] [3.8] [6400] Comparative (A)-2 (B2)-4(D)-1 (S)-1 Example 9 [100] [21.3] [3.8] [6400] Example 9 (A)-2 (B1)-4(D)-1 (S)-1 [100] [25.7] [3.8] [6400] Comparative (A)-2 (B2)-5 (D)-1(S)-1 Example 10 [100] [19.8] [3.8] [6400] Example 10 (A)-2 (B1)-5 (D)-1(S)-1 [100] [23.2] [3.8] [6400]

In Tables 1 and 2, the reference characters indicate the following. Thevalues in brackets [ ] indicate the amount (in terms of parts by weight)of the component added.

(A)-1: Polymeric compound represented by chemical formula (A1)-1 shownbelow. Polymeric compound (A1)-1 was obtained by radical polymerizationof monomers which derive the structural units constituting the polymericcompound, at a predetermined ratio. With respect to the polymericcompound (A1)-1, the weight average molecular weight (Mw) and thepolydispersity (Mw/Mn) were determined by the polystyrene equivalentvalue as measured by gel permeation chromatography (GPC). As a result,it was found that the weight average molecular weight was 7,200, and thepolydispersity was 1.69. The composition of the copolymer (ratio (molarratio) of the respective structural units within the structural formula)as determined by ¹³C-NMR was l/m=50/50.

(A)-2: Polymeric compound represented by chemical formula (A1)-2 shownbelow. Polymeric compound (A1)-2 was obtained by radical polymerizationof monomers which derive the structural units constituting the polymericcompound, at a predetermined ratio. With respect to the polymericcompound (A1)-2, the weight average molecular weight (Mw) and thepolydispersity (Mw/Mn) were determined by the polystyrene equivalentvalue as measured by gel permeation chromatography (GPC). As a result,it was found that the weight average molecular weight was 6,900, and thepolydispersity was 1.72. The composition of the copolymer (ratio (molarratio) of the respective structural units within the structural formula)as determined by ¹³C-NMR was l/m/n=30/60/10.

(B1)-1: Acid generator consisting of the compound (B1-1).

(B1)-2: Acid generator consisting of the compound (B1-2).

(B1)-3: Acid generator consisting of the compound (B1-3).

(B1)-4: Acid generator consisting of the compound (B1-4).

(B1)-5: Acid generator consisting of the compound (B1-5).

(B2)-1: Acid generator consisting of the compound (B2-1) shown below.

(B2)-2: Acid generator consisting of the compound (B2-2) shown below.

(B2)-3: Acid generator consisting of the compound (B2-3) shown below.

(B2)-4: Acid generator consisting of the compound (B2-4) shown below.

(B2)-5: Acid generator consisting of the compound (B2-5) shown below.

(D)-1: Acid diffusion control agent consisting of a compound representedby chemical formula (D1-1) shown below.

(S)-1: a mixed solvent of propylene glycol monomethyl etheracetate/propylene glycol monomethyl ether=60/40 (weight ratio).

<Formation of Resist Pattern>

Each of the resist compositions of examples and comparative examples wasapplied to an 8-inch silicon substrate which had been treated withhexamethyldisilazane (HMDS) using a spinner, and was then prebaked (PAB)on a hot plate at 110° C. for 60 seconds and dried, thereby forming aresist film having a film thickness of 50 nm.

A drawing (exposure) was carried out on the resist film using anelectron beam lithography system JEOL-JBX-9300FS (manufactured by JEOLLtd.) with acceleration voltage of 100 kV and a target size of 1:1line-and-space pattern (line width: 50 nm) (hereinafter referred to asan “LS pattern”). Then, a post exposure bake (PEB) treatment wasconducted at 100° C. for 60 seconds.

Thereafter, alkali developing was conducted for 60 seconds at 23° C. ina 2.38% by weight aqueous solution of tetramethylammonium hydroxide(TMAH) (product name: NMD-3; manufactured by Tokyo Ohka Kogyo Co.,Ltd.).

Then, water rinsing was conducted for 15 seconds using pure water.

As a result, a 1:1 LS pattern having a line width of 50 nm was formed.

[Evaluation of Optimum Exposure Dose (Eop)]

The optimum exposure dose Eop (μC/cm²) with which the LS pattern wasformed in the above formation of resist pattern was determined. Theresults are indicated under “Eop(μC/cm²)” in Tables 3 and 4.

[Evaluation of Line Width Roughness (LWR)]

With respect to the LS pattern formed in the above “formation of resistpattern”, 3a was determined as a yardstick for indicating LWR. Theresults are indicated under “LWR (nm)” in Tables 3 and 4.

“3σ” indicates a value of 3 times the standard deviation (a) (i.e., 36)(unit: nm) determined by measuring the line positions at 400 points inthe lengthwise direction of the line using a scanning electronmicroscope (product name: S-9380, manufactured by HitachiHigh-Technologies Corporation; acceleration voltage: 800V).

The smaller this 3σ value is, the lower the level of roughness on theside walls of the line, indicating that an LS pattern with a uniformwidth was obtained.

TABLE 3 Eop LWR (μC/cm²) (nm) Comparative 95 6.4 Example 1 Comparative110 5.9 Example 2 Example 1 90 5.6 Example 2 95 5.8 Comparative 95 6.6Example 3 Example 3 95 5.8 Comparative 90 6.5 Example 4 Example 4 85 5.7Comparative 85 6.6 Example 5 Example 5 80 5.7

TABLE 4 Eop LWR (μC/cm²) (nm) Comparative 100 6.3 Example 6 Comparative115 5.8 Example 7 Example 6 95 5.5 Example 7 95 5.7 Comparative 100 6.3Example 8 Example 8 95 5.6 Comparative 90 6.4 Example 9 Example 9 90 5.5Comparative 90 6.5 Example 10 Example 10 85 5.4

As seen from the results shown in Tables 3 and 4, it was confirmed that,according to the resist compositions of Examples 1 to 10, sensitivitycould be enhanced in the formation of a resist pattern, and a resistpattern having reduced roughness and a good shape could be formed.

What is claimed is:
 1. A compound represented by general formula (bp-1)shown below:

wherein R^(p1) represents an aryl group which has a substituentcontaining a halogen atom and a substituent represented by the formula:—SR^(p4); R^(p2) and R^(p3) represent an aryl group; R^(p1) representsan aryl group which has a substituent containing a halogen atom; R^(p2)and R^(p3) represent an alkyl group, and R^(p2) and R^(p3) are mutuallybonded via a divalent group represented by the formula: —SR^(p4)′ — toform a ring with the sulfur atom, R^(p1) represents an aryl group whichhas a substituent containing a halogen atom and a substituentrepresented by the formula: —SR^(p4); R^(p2) represents an aryl group;and R^(p3) represents an alkyl group, and R^(p2) and R^(p3) are mutuallybonded to form a ring with the sulfur atom, R^(p1) represents an arylgroup which has a substituent containing a halogen atom; and R^(p2) andR^(p3) represent an aryl group which have a substituent represented bythe formula: —SR^(p4), or R^(p1) and R^(p2) represent an aryl groupwhich have a substituent containing a halogen atom and a substituentrepresented by the formula: —SR^(p4); and R^(p3) represents an arylgroup, R^(p4) represents an alkyl group; R^(p4)′ represents an alkylenegroup or a single bond to form a ring; and Xp⁻ represents acounteranion.
 2. The compound according to claim 1, wherein R^(p1)represents an aryl group which have a substituent containing a halogenatom and a substituent represented by the formula: —SR^(p4); R^(p2) andR^(p3) represent an aryl group.
 3. The compound according to claim 1,wherein R^(p1) and R^(p2) represent an aryl group which have asubstituent containing a halogen atom and a substituent represented bythe formula: —SR^(p4); and R^(p3) represents an aryl group.
 4. Thecompound according to claim 1, wherein R^(p1) represents an aryl groupwhich has a substituent containing a halogen atom; R^(p2) and R^(p3)represent an alkyl group, and R^(p2) and R^(p3) are mutually bonded viaa divalent group represented by the formula: —SR^(p4)′- to form a ringwith the sulfur atom.
 5. The compound according to claim 1, whereinR^(p1) represents an aryl group which has a substituent containing ahalogen atom; and R^(p2) and R^(p3) represent an aryl group which has asubstituent represented by the formula: —SR^(p4).
 6. The compoundaccording to claim 1, wherein R^(p1) represents an aryl group which hasa substituent containing a halogen atom and a substituent represented bythe formula: —SR^(p4); R^(p2) represents an aryl group; and R^(p3)represents an alkyl group, and R^(p2) and R^(p3) are mutually bonded toform a ring with the sulfur atom.
 7. The compound according to claim 1,wherein the substituent containing a halogen atom is a halogenated alkylgroup.
 8. The compound according to claim 2, wherein the substituentcontaining a halogen atom is a halogenated alkyl group.
 9. The compoundaccording to claim 3, wherein the substituent containing a halogen atomis a halogenated alkyl group.
 10. The compound according to claim 4,wherein the substituent containing a halogen atom is a halogenated alkylgroup.
 11. The compound according to claim 5, wherein the substituentcontaining a halogen atom is a halogenated alkyl group.
 12. The compoundaccording to claim 6, wherein the substituent containing a halogen atomis a halogenated alkyl group.
 13. The compound according to claim 1,wherein the Xp⁻represent an anion selected from the group consisting ofa halogen anion, a carboxylic acid anion, and RpSO₃ ⁻, and Rp is analkyl group having 1 to 5 carbon atoms or a fluorinated alkyl grouphaving 1 to 5 carbon atoms.
 14. The compound according to claim 2,wherein the Xp⁻represents an anion selected from the group consisting ofa halogen anion, a carboxylic acid anion, and RpSO₃ ⁻, and Rp is analkyl group having 1 to 5 carbon atoms or a fluorinated alkyl grouphaving 1 to 5 carbon atoms.
 15. The compound according to claim 3,wherein the Xp⁻represents an anion selected from the group consisting ofa halogen anion, a carboxylic acid anion, and RpSO₃ ⁻, and Rp is analkyl group having 1 to 5 carbon atoms or a fluorinated alkyl grouphaving 1 to 5 carbon atoms.
 16. The compound according to claim 4,wherein the Xp⁻represents an anion selected from the group consisting ofa halogen anion, a carboxylic acid anion, and RpSO₃ ⁻, and Rp is analkyl group having 1 to 5 carbon atoms or a fluorinated alkyl grouphaving 1 to 5 carbon atoms.
 17. The compound according to claim 5,wherein the Xp⁻represents an anion selected from the group consisting ofa halogen anion, a carboxylic acid anion, and RpSO3⁻, and Rp is an alkylgroup having 1 to 5 carbon atoms or a fluorinated alkyl group having 1to 5 carbon atoms.
 18. The compound according to claim 6, wherein theXp⁻represents an anion selected from the group consisting of a halogenanion, a carboxylic acid anion, and RpSO3⁻, and Rp is an alkyl grouphaving 1 to 5 carbon atoms or a fluorinated alkyl group having 1 to 5carbon atoms.